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Mature results from a Swedish comparison study of conventional versus accelerated radiotherapy in head and neck squamous cell carcinoma – The ARTSCAN trial

Published:September 29, 2015DOI:https://doi.org/10.1016/j.radonc.2015.09.024

      Abstract

      Background and purpose

      This report contains the mature five-year data from the Swedish ARTSCAN trial including information on the influence of p16 positivity (p16+) for oropharyngeal cancers.

      Material and methods

      Patients with previously untreated squamous cell carcinoma without distant metastases of the oral cavity, oropharynx, larynx (except T1–2, N0 glottic cancers) and hypopharynx were included. Patients were randomised between accelerated fractionation (AF) (1.1 Gy + 2 Gy per day, 5 days/week for 4.5 weeks, total dose 68 Gy) and conventional fractionation (CF) (2 Gy per day, 5 days/week for 7 weeks, total dose 68 Gy). Human papillomavirus (HPV)-associated p16-expression was assessed retrospectively in tumour tissues from patients with oropharyngeal carcinoma.

      Results

      There was no significant difference in loco-regional control (LRC) between AF and CF (log-rank test p = 0.75). LRC at 5 years was 65.5% for AF and 64.9% for CF. Overall survival (OS) was similar in both arms (p = 0.99). The estimated cancer specific survival (CSS) at 5 years was 62.2% (AF) and 63.3% (CF) (p = 0.99). 206 specimens were analysed for p16 with 153 specimens (74%) identified as p16+. P16 status did not discriminate for response to AF vs. CF with regard to LRC, OS or CSS. Patients with p16+ tumours had a statistically significant better overall prognosis compared with p16− tumours.

      Conclusion

      This update confirms the results of the 2-year report. We failed to identify a positive effect resulting from AF with regards to LRC, OS and CSS. The addition of information on the HPV-associated p16 overexpression did not explain this lack of effect.

      Keywords

      The role of accelerated fractionation without total dose reduction (AF) in head and neck cancer has been the focus of several studies [
      • Zackrisson B.
      • Nilsson P.
      • Kjellén E.
      • et al.
      Two-year results from a Swedish study on conventional versus accelerated radiotherapy in head and neck squamous cell carcinoma – the ARTSCAN study.
      ,
      • Jackson S.M.
      • Weir L.M.
      • Hay J.H.
      • Tsang V.H.
      • Durham J.S.
      A randomized trial of accelerated versus conventional radiotherapy in head and neck cancer.
      ,
      • Horiot J.C.
      • Bontemps P.
      • Van Den Bogaert W.
      • et al.
      Accelerated fractionation compared to conventional fractionation improves locoregional control in the radiotherapy of advanced head and neck cancer: results of the EORTC 22851 randomized trial.
      ,
      • Fu K.K.
      • Pajak T.F.
      • Trotti A.
      • et al.
      A radiation therapy oncology group (RTOG) phase III randomized study to compare hyperfractionation and two variants of accelerated fractionation to standard fractionation radiotherapy for head and neck squamous cell carcinomas: first report of RTOG 9003.
      ,
      • Skladowski K.
      • Maciejewski B.
      • Golen M.
      • Pilecki B.
      • Przeorek W.
      • Tarnawski R.
      Randomized clinical trial on 7-days-continuous accelerated irradiation (CAIR) of head and neck cancer – report on 3-year tumor control and normal tissue toxicity.
      ,
      • Poulsen M.G.
      • Denham J.W.
      • Peters L.J.
      • et al.
      A randomised trial of accelerated and conventional radiotherapy for stage III and IV squamous carcinoma of the head and neck: a trans-tasman radiation oncology group study.
      ,
      • Hliniak A.
      • Gwiazdowska B.
      • Szutkowski Z.
      • et al.
      A multicenter randomized/controlled trial of a conventional versus modestly accelerated radiotherapy in the laryngeal cancer: influence of a 1 week shortening overall time.
      ,
      • Overgaard J.
      • Hansen H.S.
      • Specht L.
      • et al.
      Five compared with six fractions per week of conventional radiotherapy of squamous-cell carcinoma of head and neck: DAHANCA 6&7 randomised controlled trial.
      ,
      • Olmi P.
      • Crispino S.
      • Fallai C.
      • et al.
      Locoregionally advanced carcinoma of the oropharynx: conventional radiotherapy versus accelerated hyperfractionated radiotherapy versus concomitant radiotherapy and chemotherapy – a multicenter randomized trial.
      ,
      • Bourhis J.
      • Lapeyre M.
      • Tortochaux J.
      • et al.
      Phase III randomized trial of very accelerated radiation therapy compared with conventional radiation therapy in squamous cell head and neck cancer: a GORTEC trial.
      ,
      • Overgaard J.
      • Mohanti B.K.
      • Begum N.
      • et al.
      Five versus six fractions of radiotherapy per week for squamous cell carcinoma of the head and neck (IAEA-ACC study): a randomised, multicentre trial.
      ,
      • Beitler J.J.
      • Zhang Q.
      • Fu K.K.
      • et al.
      Final results of local-regional control and late toxicity of RTOG 9003: a randomized trial of altered fractionation radiation for locally advanced head and neck cancer.
      ]. A number of different treatment schedules have been applied and most of them show an improved loco-regional control (LRC) [
      • Horiot J.C.
      • Bontemps P.
      • Van Den Bogaert W.
      • et al.
      Accelerated fractionation compared to conventional fractionation improves locoregional control in the radiotherapy of advanced head and neck cancer: results of the EORTC 22851 randomized trial.
      ,
      • Fu K.K.
      • Pajak T.F.
      • Trotti A.
      • et al.
      A radiation therapy oncology group (RTOG) phase III randomized study to compare hyperfractionation and two variants of accelerated fractionation to standard fractionation radiotherapy for head and neck squamous cell carcinomas: first report of RTOG 9003.
      ,
      • Skladowski K.
      • Maciejewski B.
      • Golen M.
      • Pilecki B.
      • Przeorek W.
      • Tarnawski R.
      Randomized clinical trial on 7-days-continuous accelerated irradiation (CAIR) of head and neck cancer – report on 3-year tumor control and normal tissue toxicity.
      ,
      • Poulsen M.G.
      • Denham J.W.
      • Peters L.J.
      • et al.
      A randomised trial of accelerated and conventional radiotherapy for stage III and IV squamous carcinoma of the head and neck: a trans-tasman radiation oncology group study.
      ,
      • Bourhis J.
      • Lapeyre M.
      • Tortochaux J.
      • et al.
      Phase III randomized trial of very accelerated radiation therapy compared with conventional radiation therapy in squamous cell head and neck cancer: a GORTEC trial.
      ,
      • Overgaard J.
      • Mohanti B.K.
      • Begum N.
      • et al.
      Five versus six fractions of radiotherapy per week for squamous cell carcinoma of the head and neck (IAEA-ACC study): a randomised, multicentre trial.
      ]. In [
      • Jackson S.M.
      • Weir L.M.
      • Hay J.H.
      • Tsang V.H.
      • Durham J.S.
      A randomized trial of accelerated versus conventional radiotherapy in head and neck cancer.
      ,
      • Horiot J.C.
      • Bontemps P.
      • Van Den Bogaert W.
      • et al.
      Accelerated fractionation compared to conventional fractionation improves locoregional control in the radiotherapy of advanced head and neck cancer: results of the EORTC 22851 randomized trial.
      ], the increased LRC is gained at the expense of greater late morbidity. Altered fractionation, both AF and hyperfractionated (HF), has been the focus of meta-analyses [
      • Bourhis J.
      • Overgaard J.
      • Audry H.
      • et al.
      Hyperfractionated or accelerated radiotherapy in head and neck cancer: a meta-analysis.
      ,
      • Baujat B.
      • Bourhis J.
      • Blanchard P.
      • et al.
      Hyperfractionated or accelerated radiotherapy for head and neck cancer.
      ] where the effect of AF versus conventional fractionation (CF) on overall survival (OS) is estimated to be +2% at 5 years. The benefit of altered fractionation is greater in patients with younger age and advanced primary tumours [
      • Baujat B.
      • Bourhis J.
      • Blanchard P.
      • et al.
      Hyperfractionated or accelerated radiotherapy for head and neck cancer.
      ]. It is also reported that AF has a greater efficiency for primary tumours compared with node metastases [
      • Overgaard J.
      • Mohanti B.K.
      • Begum N.
      • et al.
      Five versus six fractions of radiotherapy per week for squamous cell carcinoma of the head and neck (IAEA-ACC study): a randomised, multicentre trial.
      ]. In a recent report on the final results of RTOG 9003 [
      • Beitler J.J.
      • Zhang Q.
      • Fu K.K.
      • et al.
      Final results of local-regional control and late toxicity of RTOG 9003: a randomized trial of altered fractionation radiation for locally advanced head and neck cancer.
      ] it was concluded that HF, but not AF, improved loco-regional control (LRC) and OS without increasing the risk for late side effects.
      In oropharyngeal cancers, the presence of human papilloma virus (HPV) is shown to have an independent prognostic significance [
      • Ang K.K.
      • Harris J.
      • Wheeler R.
      • et al.
      Human papillomavirus and survival of patients with oropharyngeal cancer.
      ]. Although HPV may be present in other tumour sites of the head and neck region, it seems to have a prognostic influence only on the oropharyngeal cancer patients [
      • Lassen P.
      • Primdahl H.
      • Johansen J.
      • et al.
      Impact of HPV-associated p16-expression on radiotherapy outcome in advanced oropharynx and non-oropharynx cancer.
      ]. To explore the effects of HPV association in oropharyngeal cancer on the results of the present study, immunohistochemical detection of HPV-associated p16-expression was performed.
      The preliminary two-year follow up of the present study [
      • Zackrisson B.
      • Nilsson P.
      • Kjellén E.
      • et al.
      Two-year results from a Swedish study on conventional versus accelerated radiotherapy in head and neck squamous cell carcinoma – the ARTSCAN study.
      ] failed to show any statistically significant benefit from AF concerning LRC and OS. The acute toxicity was more severe in the AF group while there was no evidence for a difference in late complications. The present report contains the mature five-year data from the Swedish ARTSCAN trial including information on the influence of HPV measured as p16 positivity (p16+) for oropharyngeal cancers. Possible differential effects from fractionation on the patterns of recurrence for primary tumours vs. nodal and distant are investigated.

      Materials and method

      Objectives and end points

      The primary objective of the present report was to compare the five-year LRC of radiotherapy (RT) given as AF, delivered in 4.5–5 weeks versus CF in 7 weeks with a prescribed tumour dose of 68 Gy in both treatment arms. Secondary objectives were: OS, cancer-specific survival (CSS), treatment-related morbidity, variations in outcome in different sub-sites and stages, and differences in patterns of loco-regional recurrences with respect to treatment type. During the follow up period, the HPV association with oropharyngeal cancers and the related beneficial influence on prognosis has been recognised. Therefore a new objective was to analyse the impact of HPV association on the outcome of AF.

      Patients, trial design and radiotherapy

      The patient characteristics and the methods of the study have been described in detail previously [
      • Zackrisson B.
      • Nilsson P.
      • Kjellén E.
      • et al.
      Two-year results from a Swedish study on conventional versus accelerated radiotherapy in head and neck squamous cell carcinoma – the ARTSCAN study.
      ,
      • Johansson K.A.
      • Nilsson P.
      • Zackrisson B.
      • et al.
      The quality assurance process for the ARTSCAN head and neck study – a practical interactive approach for QA in 3DCRT and IMRT.
      ]. In brief, the study originally included 750 patients with squamous cell carcinoma of the oral cavity, oropharynx, larynx (except T1–2, N0 glottic cancers) and hypopharynx. Patients with distant metastases, prior surgery and/or chemotherapy were excluded. Patients were randomised between AF (1.1 Gy + 2 Gy per day, 5 days/week for 4.5 weeks, total dose 68 Gy) and CF (2 Gy per day, 5 days/week for 7 weeks, total dose 68 Gy). In AF the two daily fractions were separated by at least 7 h. The use of CT-based three-dimensional conformal radiotherapy (3DCRT) and/or intensity-modulated radiotherapy (IMRT) was mandatory. Dose prescriptions were made according to ICRU specifications [

      International Commission on Radiation Units and Measurements, I. Prescribing, recording and reporting photon beam therapy report 50. Bethesda, MD; 1993.

      ,

      International Commission on Radiation Units and Measurements, I, (Supplement to ICRU Report 50). Prescribing, recording, and reporting photon beam therapy. Bethesda, MD; 1999.

      ]. About 10% of all patients received IMRT. They were included during the last years of the recruitment period. A comprehensive QA-programme was performed to monitor the treatment [
      • Johansson K.A.
      • Nilsson P.
      • Zackrisson B.
      • et al.
      The quality assurance process for the ARTSCAN head and neck study – a practical interactive approach for QA in 3DCRT and IMRT.
      ].

      Oropharyngeal cancers and p16 analysis

      Three hundred patients with oropharyngeal cancer from the four largest centres in Sweden were selected for retrieval of original paraffin embedded tumour material. The retrieved tumour blocks were processed as follows: tumour biopsy sections (4–5 μm) were de-paraffinised and rehydrated, with antigen retrieval in citrate buffer (pH 6) and unspecific binding sites blocked with 1.5% horse serum in PBS. The sections were then stained with mAb p16INKA4a (clone: JC8, dilution 1:100, Santa Cruz Biotech, Santa Cruz, CA, USA) at +8 °C overnight, before incubation for 45 min. with biotinylated anti-mouse antibody (dilution 1:200, Vector Laboratories, Burlingame, CA, USA). Alternatively, the slides were stained with the CINtec® p16 Histology (805-4713), Ventana Medical Systems Inc., Arizona, USA by following the same protocol with the exception of incubation with the antibody for 1 h at room temperature. For antigen detection, the avidin–biotin–peroxidase complex (ABC) kit (Vectastain, Vector Laboratories, Burlingame, CA, USA) was used. Slides developed in chromogen 3′-diaminobenzydine (DAB) (Vector Laboratories, Burlingame, CA, USA) and counterstained with haematoxylin were then washed and dehydrated, and then cover mounted using VectaMount permanent mounting media (Vector Laboratories, Burlingame, CA, USA). The p16 staining was regarded as positive if >70% of the tumour cells were strongly p16-positive [
      • Beitler J.J.
      • Zhang Q.
      • Fu K.K.
      • et al.
      Final results of local-regional control and late toxicity of RTOG 9003: a randomized trial of altered fractionation radiation for locally advanced head and neck cancer.
      ].

      Statistical considerations

      Similar statistical considerations as previously reported in the two-year follow up [
      • Zackrisson B.
      • Nilsson P.
      • Kjellén E.
      • et al.
      Two-year results from a Swedish study on conventional versus accelerated radiotherapy in head and neck squamous cell carcinoma – the ARTSCAN study.
      ] were made in this analysis of the five-year data. However, to conform to the literature, all follow up is calculated from the date of randomisation instead of the treatment start. Loss of LRC was defined as clinical and/or pathological persistence or recurrence of tumour (either locally or regionally) after the primary treatment. If the patient was never considered to be free of tumour the time to loss of LRC was set to zero.
      Differences between groups were evaluated by the chi-squared test or Fisher’s exact test for categorical variables and the Mann–Whitney test for continuous variables. LRC, OS and CSS were estimated by the Kaplan–Meier method and compared by the log-rank test and hazard ratios (HR) with [95% CI]. HR were defined so that HR <1 indicates a lower risk for the AF arm. All tests were two-sided and p-value of less than 0.05 was considered statistically significant.

      Results

      Seven hundred fifty patients were included in the study between November 1998 and June 2006. Seventeen patients were considered non-eligible (8 in CF and 9 in AF, respectively) leaving 733 patients for evaluation [
      • Zackrisson B.
      • Nilsson P.
      • Kjellén E.
      • et al.
      Two-year results from a Swedish study on conventional versus accelerated radiotherapy in head and neck squamous cell carcinoma – the ARTSCAN study.
      ]. When the ARTSCAN database was closed in August 2012 all patients had been followed for 5 years after the end of radiotherapy. Thereafter, only survival and cause of death data were obtained from The Swedish Health and Welfare Statistical Database on Cause of Death. Median follow-up times for LRC and OS were 5.3 years and 9.1 years, respectively.
      At the time of analysis 300 (150 in each treatment arm) of the 733 eligible patients were alive. Two hundred seventy patients (134 in AF group and 136 in CF) had died from the disease (loco-regional failure and/or metastatic). Four patients died from treatment related toxicity (two in each arm). Death from secondary cancer was encountered in 67 cases (36 AF and 31 CF). In 87 cases (41 AF and 46 CF) there were other known causes while the cause of death could not be retrieved in 5 cases (3 AF and 2 CF).

      Patient characteristics

      Demographics of the patients are described in [
      • Zackrisson B.
      • Nilsson P.
      • Kjellén E.
      • et al.
      Two-year results from a Swedish study on conventional versus accelerated radiotherapy in head and neck squamous cell carcinoma – the ARTSCAN study.
      ]. The treatment arms were well balanced with regard to age, sex, performance status, initial haemoglobin concentration (Hb), T stage, N stage and tumour site. The stage distribution was as follows: stage I n = 31 (4.2%), II n = 94 (12.8%), III n = 203 (27.7%) and IV n = 405 (55.3%).

      Tumour response and survival

      All eligible patients

      There was no significant difference in LRC between the two trial arms (p = 0.75). LRC at 5 years estimated by the Kaplan–Meier method was 65.5% in the AF treatment arm and 64.9% in the CF treatment arm (Fig. 1). In a separate analysis LRC was also estimated considering death as a competing risk. The correction had only a very small and non-significant effect on the estimates and not at all on the relation between outcomes. Data from this analysis is therefore not presented.
      Figure thumbnail gr1
      Fig. 1Loco-regional control as function of fractionation schedule.
      The major prognostic factors for LRC identified by univariate Kaplan–Meier estimation in the two-year analysis remained, i.e. age, KPS, Hb, T stage, smoking and tumour site. Neither gender nor presence of lymph-node metastases (N0 vs. N+) showed any statistically significant impact on LRC (Table 1).
      Table 1Patient and disease characteristics versus LRC.
      VariablesGroupingKaplan–Meier-estimated LRC at 5 yrs (%)Log-rank p-valueHR [95% CI]
      Patient characteristics
      Age⩽60 y74.6<0.00010.53 [0.41;0.69]
      >60 y56.7
      GenderFemales65.90.670.94 [0.71;1.26]
      Males65.1
      Karnofsky score10078.4<0.00010.37 [0.28;0.48]
      <10051.9
      Haemoglobin
      Incomplete data: Hb n=623 and smoking status n=531.
      >140 g/l74.1<0.00010.56 [0.42;0.75]
      ⩽140 g/l57.6
      Smoking at start of RT
      Incomplete data: Hb n=623 and smoking status n=531.
      No71.20.00040.59 [0.44;0.80]
      Yes57.1
      Disease characteristics
      T stageT190.10.00050.31 [0.16;0.63]
      T272.1
      T272.10.0580.73 [0.52;1.02]
      T363.5
      T363.5<0.00010.53 [0.39;0.73]
      T443.0
      Nodal statusN063.60.681.05 [0.82;1.36]
      N+66.3
      Tumour siteOropharynx76.70.0160.87 [0.77;0.98]
      Larynx66.8
      Larynx66.80.0030.75 [0.61;0.91]
      Oral cavity48.9
      Oral cavity48.90.290.83 [0.57;1.20]
      Hypopharynx41.4
      Larynx66.8<0.00010.46 [0.32;0.67]
      Hypopharynx41.4
      low asterisk Incomplete data: Hb n = 623 and smoking status n = 531.
      Overall survival did not differ between the treatment groups (p = 0.99). Median OS (95% CI) was 5.1 y (3.3–6.9 y) and 5.4 y (3.7–7.1 y) in the AF and CF group, respectively (Fig. 2).
      Figure thumbnail gr2
      Fig. 2Overall survival as function of fractionation schedule.
      Estimated CSS at 5 years was 62.2% (AF) and 63.3% (CF) (p = 0.99).
      There was no statistically significant difference in the patterns of failure (T, N, M) between the treatment arms (p = 0.20) (Table 2).
      Table 2Patterns of first failure.
      Site of failureAF

      N = 366
      CF

      N = 367
      n%n%
      T42(11.5)54(14.7)
      N16(4.4)21(5.7)
      T + N48(13.1)40(10.9)
      T + M2(0.5)3(0.8)
      N + M5(1.4)0(0.0)
      T + N + M3(0.8)3(0.8)
      M26(7.1)21(5.7)
      (no failure)224(61.2)225(61.3)
      We performed multivariate Cox regression analyses with LRC and OS as dependent variables including the prognostic factors in Table 1 and treatment arm as covariates. All univariate statistically significant variables contributed significantly to the model while treatment arm did not (corrected HR = 0.83 [0.64;1.08], p = 0.17 for LRC and HR = 0.89 [0.73;1.08], p = 0.23 for OS).

      Sub-group analyses

      The outcome with respect to LRC for different tumour sub-sites are reported in Table 3 and shown in Fig. 3a–d. There were no significant differences in LRC between AF and CF within the different patient subgroups of Table 1. In the previous report [
      • Zackrisson B.
      • Nilsson P.
      • Kjellén E.
      • et al.
      Two-year results from a Swedish study on conventional versus accelerated radiotherapy in head and neck squamous cell carcinoma – the ARTSCAN study.
      ] a non-significant trend for better LRC in oral cancers after AF vs. CF was noted. The trend remained in the present update (p = 0.10).
      Table 3LRC, OS and CSS per tumour site.
      Tumour siteKaplan–Meier estimated

      LRC/OS/CSS at 5 yrs (%)
      Log-rank

      p-value
      HR [95% CI]

      AF vs. CF
      AFCF
      LRC
      Larynx64.269.20.511.21 [0.68;2.13]
      Hypopharynx38.744.30.831.05 [0.65;1.70]
      Oral cavity57.940.60.100.63 [0.36;1.13]
      Oropharynx76.676.80.981.00 [0.65;1.56]
       P16 pos82.583.60.980.99 [0.45;2.17]
       P16 neg72.046.40.230.57 [0.22;1.49]
      OS
      Larynx45.547.40.871.03 [0.70;1.52]
      Hypopharynx18.027.40.311.21 [0.83;1.78]
      Oral cavity42.935.30.860.96 [0.60;1.52]
      Oropharynx65.964.00.630.93 [0.67;1.27]
       P16 pos78.573.00.720.90 [0.51;1.58]
       P16 neg36.032.10.280.70 [0.36;1.34]
      CSS
      Larynx63.469.00.651.14 [0.65;2.00]
      Hypopharynx28.837.40.471.18 [0.75;1.83]
      Oral cavity57.345.50.280.72 [0.41;1.29]
      Oropharynx73.174.50.931.02 [0.68;1.52]
       P16 pos84.276.60.300.70 [0.35;1.39]
       P16 neg53.348.80.690.85 [0.37;1.92]
      Figure thumbnail gr3
      Fig. 3Loco-regional control as function of fractionation schedule for the different tumour subgroups: (a) larynx, (b) hypopharynx, (c) oral cavity, and (d) oropharynx.
      For laryngeal cancers the estimated median (95% CI) OS time was 4.3 (2.7–5.8) years for AF vs. 3.9 (1.6–6.2) years for CF. The corresponding figures for hypopharyngeal cancers were 1.5 (1.0–2.0) vs. 1.5 (1.1–1.9) years, and for cancers of the oral cavity 3.1 (0.1–6.3) vs. 2.2 (0.7–3.6) years (Table 3). For oropharyngeal tumours, the Kaplan–Meier estimated OS at 5 and 10 years were 66% and 58% for AF versus 64% and 57% for CF, respectively. CSS showed a pattern similar to that of LRC and OS without any statistically significant difference between AF and CF (Table 3).
      The response of T1–2 tumours was similar for AF and CF with an estimated LRC at 5 years of 75.7% and 78.1%, respectively (p = 0.57). Previously, we reported a trend towards better LRC for AF at 2 years for T3–4 tumours. This trend was reduced in this update; LRC 55.7% for AF vs. 51.7% for CF at 5 years (p = 0.29). There was no significant difference in LRC between AF vs. CF for patients with N0 (p = 0.10) and N+ (p = 0.38) tumours.
      Analysis of any presence of p16 overexpression was performed for oropharyngeal cancers. Paraffin embedded tumour specimens could be retrieved and analysed from 206 of the 357 evaluable patients with oropharyngeal cancer. For assessment of possible selection bias in the group whose tumour material was analysed, the groups with known p16 status vs. unknown were compared with respect to LRC and OS. No difference in LRC (HR = 0.86 [0.55;1.34], p = 0.51) or OS (HR = 0.97 [0.70;1.34], p = 0.86) could be detected. Updated demographics for oropharyngeal cancer patients with known p16 status are shown in Table 4. The patients’ characteristics differ significantly between patients with p16 overexpression vs. without. The p16-overexpressing patients had lower T stage, higher Karnofsky performance score (KPS), younger age and were less frequently smoking.
      Table 4Patient characteristics for the subjects with known p16 status.
      p16 positivep16 negativep-value
      n = 153(%)n = 53(%)
      Age at randomisation
       Median (range)57(35–79)60(37–83)0.0076
      Gender0.36
       Male118(77.1)37(69.8)
       Female35(22.9)16(30.2)
       Total153(100)53(100.0)
      Karnofsky index0.0002
       <10047(32.2)32(62.7)
       10099(67.8)19(37.3)
       Total146(100.0)51(100.0)
      Haemoglobin conc.1.00
       ⩽14068(52.3)23(51.1)
       >14062(47.7)22(48.9)
       Total130(100.0)45(100.0)
      Smoker
      Active smoker at start of RT (patient reported).
      <0.0001
       Yes19(15.2)30(76.9)
       No106(84.8)9(23.1)
       Total125(100.0)39(100.0)
      T stage0.016
       T130(19.6)5(9.4)
       T266(43.1)15(28.3)
       T331(20.3)19(35.8)
       T426(17.0)14(26.4)
       Total153(100.0)53(100.0)
      Nodal status0.23
       N026(17.0)14(26.4)
       N1-N2B96(62.7)32(60.4)
       N2C-N331(20.3)7(13.2)
      Total153(100.0)53(100.0)
      Distant metastases1.00
       No136(88.9)47(88.7)
       Yes17(11.1)6(11.3)
       Total153(100.0)53(100.0)
      RT treatment arm0.63
       CF74(48.4)28(52.8)
       AF79(51.6)25(47.2)
       Total153(100.0)53(100.0)
      low asterisk Active smoker at start of RT (patient reported).
      The 206 patients with oropharyngeal cancer for whom we were able to retrospectively analyse p16 status were assessed with regard to differential response to AF vs. CF. The p16 status of the tumours did not change the response to AF vs. CF with regard to LRC, OS or CSS (Table 3). A statistically significant better overall prognosis was found, however, for p16+ compared with p16− tumours (Table 5).
      Table 5LRC, OS and CSS for oropharynx cancer patients with known p16 status.
      Tumour siteKaplan–Meier estimated

      LRC/OS/CSS at 5 yrs (%)
      Log-rank

      p-value
      HR [95% CI]

      P16+ vs. p16−
      p16+p16−
      LRC83.061.40.00080.37

      [0.20;0.68]
      OS75.834.0<0.00010.32

      [0.21;0.49]
      CSS80.451.2<0.00010.36

      [0.21;0.61]

      Morbidity

      The acute morbidity was reported in [
      • Zackrisson B.
      • Nilsson P.
      • Kjellén E.
      • et al.
      Two-year results from a Swedish study on conventional versus accelerated radiotherapy in head and neck squamous cell carcinoma – the ARTSCAN study.
      ] and was significantly worse in the AF group. Tube feeding was more common in the AF group but there was no difference in weight loss observed between the study groups [
      • Ottosson S.
      • Zackrisson B.
      • Kjellén E.
      • Nilsson P.
      • Laurell G.
      Weight loss in patients with head and neck cancer during and after conventional and accelerated radiotherapy.
      ]. Up to 5 years of follow-up showed no significant difference in severe late reactions observed between the treatments. The number of patients with exposed bone or bone necrosis was 7.8% in the AF and 5.6% in the CF group (p = 0.38). No case of severe fibrosis was reported. In the CF group 4 patients had a tracheostomy due to side effects versus none in AF. No case of unexpected spinal injury was observed. The incidence of trismus showed a dependence of dose to mastication structures but was not significantly different between the fractionation schedules [
      • Lindblom U.
      • Gärskog O.
      • Kjellén E.
      • et al.
      Radiation-induced trismus in the ARTSCAN head and neck trial.
      ].

      Discussion

      Compared with the two-year report of the present study [
      • Zackrisson B.
      • Nilsson P.
      • Kjellén E.
      • et al.
      Two-year results from a Swedish study on conventional versus accelerated radiotherapy in head and neck squamous cell carcinoma – the ARTSCAN study.
      ], the results here are very similar. No statistically significant difference between AF and CF concerning LRC, OS and CSS could be identified. Neither was there any significant impact of the fractionation on the incidence or severity in the assessed late morbidity. Factors like age, T-stage, N-stage or tumour site did not show any influence on the response to AF vs. CF. The only exception was a strong but non-significant trend towards a higher LRC for cancers in the oral cavity. This finding is within the scope of an ongoing clinical trial (ISRCTN00608410). In previous reports, a statistically significant improved LRC with AF was established [
      • Horiot J.C.
      • Bontemps P.
      • Van Den Bogaert W.
      • et al.
      Accelerated fractionation compared to conventional fractionation improves locoregional control in the radiotherapy of advanced head and neck cancer: results of the EORTC 22851 randomized trial.
      ,
      • Fu K.K.
      • Pajak T.F.
      • Trotti A.
      • et al.
      A radiation therapy oncology group (RTOG) phase III randomized study to compare hyperfractionation and two variants of accelerated fractionation to standard fractionation radiotherapy for head and neck squamous cell carcinomas: first report of RTOG 9003.
      ,
      • Skladowski K.
      • Maciejewski B.
      • Golen M.
      • Pilecki B.
      • Przeorek W.
      • Tarnawski R.
      Randomized clinical trial on 7-days-continuous accelerated irradiation (CAIR) of head and neck cancer – report on 3-year tumor control and normal tissue toxicity.
      ,
      • Overgaard J.
      • Hansen H.S.
      • Specht L.
      • et al.
      Five compared with six fractions per week of conventional radiotherapy of squamous-cell carcinoma of head and neck: DAHANCA 6&7 randomised controlled trial.
      ,
      • Bourhis J.
      • Lapeyre M.
      • Tortochaux J.
      • et al.
      Phase III randomized trial of very accelerated radiation therapy compared with conventional radiation therapy in squamous cell head and neck cancer: a GORTEC trial.
      ,
      • Overgaard J.
      • Mohanti B.K.
      • Begum N.
      • et al.
      Five versus six fractions of radiotherapy per week for squamous cell carcinoma of the head and neck (IAEA-ACC study): a randomised, multicentre trial.
      ]. This was also the result of a meta-analysis by Bourhis et al. [
      • Bourhis J.
      • Overgaard J.
      • Audry H.
      • et al.
      Hyperfractionated or accelerated radiotherapy in head and neck cancer: a meta-analysis.
      ]. In all studies except one [
      • Skladowski K.
      • Maciejewski B.
      • Golen M.
      • Pilecki B.
      • Przeorek W.
      • Tarnawski R.
      Randomized clinical trial on 7-days-continuous accelerated irradiation (CAIR) of head and neck cancer – report on 3-year tumor control and normal tissue toxicity.
      ], no statistically significant difference in OS was detected. In [
      • Bourhis J.
      • Overgaard J.
      • Audry H.
      • et al.
      Hyperfractionated or accelerated radiotherapy in head and neck cancer: a meta-analysis.
      ] an improvement of OS at 5 years of 2% was estimated. More recently, the result of the RTOG 9003 study was reported by Beitler et al. [
      • Beitler J.J.
      • Zhang Q.
      • Fu K.K.
      • et al.
      Final results of local-regional control and late toxicity of RTOG 9003: a randomized trial of altered fractionation radiation for locally advanced head and neck cancer.
      ]. The initially reported favourable outcome of continuous AF was no longer statistically significant. In addition to this, Bourhis et al. [
      • Bourhis J.
      • Sire C.
      • Graff P.
      • et al.
      Concomitant chemoradiotherapy versus acceleration of radiotherapy with or without concomitant chemotherapy in locally advanced head and neck carcinoma (GORTEC 99–02): an open-label phase 3 randomised trial.
      ] found no difference in effectiveness between AF and CF when combined with concomitant cisplatinum. The results from the present study as well as [
      • Beitler J.J.
      • Zhang Q.
      • Fu K.K.
      • et al.
      Final results of local-regional control and late toxicity of RTOG 9003: a randomized trial of altered fractionation radiation for locally advanced head and neck cancer.
      ,
      • Bourhis J.
      • Sire C.
      • Graff P.
      • et al.
      Concomitant chemoradiotherapy versus acceleration of radiotherapy with or without concomitant chemotherapy in locally advanced head and neck carcinoma (GORTEC 99–02): an open-label phase 3 randomised trial.
      ] thus question the value of AF. In the present study, the LRC at 5 years of 64.9% in the CF arm was comparatively high to those reported by many other studies. This might have led to a smaller relative difference between AF and CF that would perhaps not then be detected. The varying results between the mentioned studies of AF are not explained by obvious differences in the patient characteristics in the respective materials. In recent years, HPV associated oropharyngeal cancer has been identified as a disease with a better prognosis compared with oropharyngeal cancers without this association [
      • Lassen P.
      • Primdahl H.
      • Johansen J.
      • et al.
      Impact of HPV-associated p16-expression on radiotherapy outcome in advanced oropharynx and non-oropharynx cancer.
      ,
      • Lassen P.
      The role of Human papillomavirus in head and neck cancer and the impact on radiotherapy outcome.
      ]. In concordance with many other studies, oropharyngeal carcinoma patients constitute a large proportion of the material in this report. It is well known that the proportion of HPV association in oropharyngeal cancers may vary between different populations, e.g. [
      • Näsman A.
      • Nordfors C.
      • Holzhauser S.
      • et al.
      Incidence of human papillomavirus positive tonsillar and base of tongue carcinoma: a stabilisation of an epidemic of viral induced carcinoma?.
      ,
      • Antonsson A.
      • Neale R.E.
      • Boros S.
      • et al.
      Human papillomavirus status and p16(INK4A) expression in patients with mucosal squamous cell carcinoma of the head and neck in Queensland, Australia.
      ]. For that reason we collected original diagnostic material from the oropharyngeal cancer patients. From the original 357 evaluable patients material could be retrieved and analysed from 206 (58%). Immunohistochemical evaluation of p16 was performed, as p16 is a prognostic factor in oropharyngeal carcinoma [
      • Chung C.H.
      • Zhang Q.
      • Kong C.S.
      • et al.
      P16 protein expression and human papillomavirus status as prognostic biomarkers of non oropharyngeal head and neck squamous cell carcinoma.
      ] and has a strong association to HPV, which makes it a suitable surrogate marker [
      • Thomas J.
      • Primeaux T.
      Is p16 immunohistochemistry a more cost-effective method for identification of human papilloma virus-associated head and neck squamous cell carcinoma?.
      ]. The proportion of p16+ patients was 74% among the 206 analysed cases. To assess possible selection bias, the 206 patients with known p16 status were compared with the 151 patients with unknown p16 status and were found to have similar LRC, OS and CSS (p = 0.51, p = 0.86 and p = 0.98, respectively). The p16+ patients had a significantly better prognosis with regard to LRC, OS and CSS than the p16− patients. There was a statistically non-significant trend towards a higher proportion of mainly LRC with AF than CF in p16− patients. However, the total number of p16− patients was small (n = 53) and probably insufficient to detect any true difference in response between AF and CF. One hypothesis that might be raised is that other studies with a smaller proportion of p16+ patients may have detected a difference between AF and CF in such cases, while this study fails to do so. In this respect the present study is inconclusive. Lassen et al. [
      • Lassen P.
      • Eriksen J.
      • Krogdahl A.
      • et al.
      The influence of HPV-associated p16-expression on accelerated fractionated radiotherapy in head and neck cancer: evaluation of the randomised DAHANCA 6&7 trial.
      ] concluded that the beneficial effect from AF was independent of p16 status, which speaks against our finding of a trend for p16− patients only.
      In conclusion this update confirms the results of the previous report [
      • Zackrisson B.
      • Nilsson P.
      • Kjellén E.
      • et al.
      Two-year results from a Swedish study on conventional versus accelerated radiotherapy in head and neck squamous cell carcinoma – the ARTSCAN study.
      ]. We failed to identify a positive effect from AF regarding LRC, OS and CSS. The addition of information on the HPV associated p16 overexpression did not explain this lack of effect. Small effects may be obscured by the fact that the overall outcome is comparatively good in the present study. This may hamper the statistical inference and demand for even larger studies or meta-analyses. Furthermore, a low proportion of p16− oropharyngeal tumours prohibits conclusions on this sub-group.

      Conflict of interest statement

      The authors have nothing to disclose.

      Acknowledgements

      This work was supported by grants from the Swedish Cancer Society , the Cancer Research Foundation of Northern Sweden , Laryngfonden (Sweden) and the Cancer Society in Stockholm. The study was made possible by the commitment from the staff at all the participating centres in the ARTSCAN study: Umeå University Hospital, Lund University Hospital, Karolinska University Hospital, Stockholm, Sahlgrenska University Hospital, Göteborg, Örebro University Hospital, Karlstad Central Hospital, Linköping University Hospital, Gävle hospital, Ryhov County Hospital, Jönköping, Uppsala University Hospital.

      References

        • Zackrisson B.
        • Nilsson P.
        • Kjellén E.
        • et al.
        Two-year results from a Swedish study on conventional versus accelerated radiotherapy in head and neck squamous cell carcinoma – the ARTSCAN study.
        Radiother Oncol. 2011; 100: 41-48
        • Jackson S.M.
        • Weir L.M.
        • Hay J.H.
        • Tsang V.H.
        • Durham J.S.
        A randomized trial of accelerated versus conventional radiotherapy in head and neck cancer.
        Radiother Oncol. 1997; 43: 39-46
        • Horiot J.C.
        • Bontemps P.
        • Van Den Bogaert W.
        • et al.
        Accelerated fractionation compared to conventional fractionation improves locoregional control in the radiotherapy of advanced head and neck cancer: results of the EORTC 22851 randomized trial.
        Radiother Oncol. 1997; 44: 39-46
        • Fu K.K.
        • Pajak T.F.
        • Trotti A.
        • et al.
        A radiation therapy oncology group (RTOG) phase III randomized study to compare hyperfractionation and two variants of accelerated fractionation to standard fractionation radiotherapy for head and neck squamous cell carcinomas: first report of RTOG 9003.
        Int J Radiat Oncol Biol Phys. 2000; 48: 7-16
        • Skladowski K.
        • Maciejewski B.
        • Golen M.
        • Pilecki B.
        • Przeorek W.
        • Tarnawski R.
        Randomized clinical trial on 7-days-continuous accelerated irradiation (CAIR) of head and neck cancer – report on 3-year tumor control and normal tissue toxicity.
        Radiother Oncol. 2000; 55: 101-110
        • Poulsen M.G.
        • Denham J.W.
        • Peters L.J.
        • et al.
        A randomised trial of accelerated and conventional radiotherapy for stage III and IV squamous carcinoma of the head and neck: a trans-tasman radiation oncology group study.
        Radiother Oncol. 2001; 60: 113-122
        • Hliniak A.
        • Gwiazdowska B.
        • Szutkowski Z.
        • et al.
        A multicenter randomized/controlled trial of a conventional versus modestly accelerated radiotherapy in the laryngeal cancer: influence of a 1 week shortening overall time.
        Radiother Oncol. 2002; 62: 1-10
        • Overgaard J.
        • Hansen H.S.
        • Specht L.
        • et al.
        Five compared with six fractions per week of conventional radiotherapy of squamous-cell carcinoma of head and neck: DAHANCA 6&7 randomised controlled trial.
        Lancet. 2003; 362: 933-940
        • Olmi P.
        • Crispino S.
        • Fallai C.
        • et al.
        Locoregionally advanced carcinoma of the oropharynx: conventional radiotherapy versus accelerated hyperfractionated radiotherapy versus concomitant radiotherapy and chemotherapy – a multicenter randomized trial.
        Int J Radiat Oncol Biol Phys. 2003; 55: 78-92
        • Bourhis J.
        • Lapeyre M.
        • Tortochaux J.
        • et al.
        Phase III randomized trial of very accelerated radiation therapy compared with conventional radiation therapy in squamous cell head and neck cancer: a GORTEC trial.
        J Clin Oncol. 2006; 24: 2873-2878
        • Overgaard J.
        • Mohanti B.K.
        • Begum N.
        • et al.
        Five versus six fractions of radiotherapy per week for squamous cell carcinoma of the head and neck (IAEA-ACC study): a randomised, multicentre trial.
        Lancet Oncol. 2010; 11: 553-560
        • Beitler J.J.
        • Zhang Q.
        • Fu K.K.
        • et al.
        Final results of local-regional control and late toxicity of RTOG 9003: a randomized trial of altered fractionation radiation for locally advanced head and neck cancer.
        Int J Radiat Oncol Biol Phys. 2014; 89: 13-20
        • Bourhis J.
        • Overgaard J.
        • Audry H.
        • et al.
        Hyperfractionated or accelerated radiotherapy in head and neck cancer: a meta-analysis.
        Lancet. 2006; 368: 843-854
        • Baujat B.
        • Bourhis J.
        • Blanchard P.
        • et al.
        Hyperfractionated or accelerated radiotherapy for head and neck cancer.
        Cochrane Database Syst Rev. 2010; 12
        • Ang K.K.
        • Harris J.
        • Wheeler R.
        • et al.
        Human papillomavirus and survival of patients with oropharyngeal cancer.
        N Engl J Med. 2010; 363: 24-35
        • Lassen P.
        • Primdahl H.
        • Johansen J.
        • et al.
        Impact of HPV-associated p16-expression on radiotherapy outcome in advanced oropharynx and non-oropharynx cancer.
        Radiother Oncol. 2014; 113: 310-316
        • Johansson K.A.
        • Nilsson P.
        • Zackrisson B.
        • et al.
        The quality assurance process for the ARTSCAN head and neck study – a practical interactive approach for QA in 3DCRT and IMRT.
        Radiother Oncol. 2008; 87: 290-299
      1. International Commission on Radiation Units and Measurements, I. Prescribing, recording and reporting photon beam therapy report 50. Bethesda, MD; 1993.

      2. International Commission on Radiation Units and Measurements, I, (Supplement to ICRU Report 50). Prescribing, recording, and reporting photon beam therapy. Bethesda, MD; 1999.

        • Ottosson S.
        • Zackrisson B.
        • Kjellén E.
        • Nilsson P.
        • Laurell G.
        Weight loss in patients with head and neck cancer during and after conventional and accelerated radiotherapy.
        Acta Oncol. 2013; 52: 711-718
        • Lindblom U.
        • Gärskog O.
        • Kjellén E.
        • et al.
        Radiation-induced trismus in the ARTSCAN head and neck trial.
        Acta Oncol. 2014; 53: 620-627
        • Bourhis J.
        • Sire C.
        • Graff P.
        • et al.
        Concomitant chemoradiotherapy versus acceleration of radiotherapy with or without concomitant chemotherapy in locally advanced head and neck carcinoma (GORTEC 99–02): an open-label phase 3 randomised trial.
        Lancet Oncol. 2012; 13: 145-153
        • Lassen P.
        The role of Human papillomavirus in head and neck cancer and the impact on radiotherapy outcome.
        Radiother Oncol. 2010; 95: 371-380
        • Näsman A.
        • Nordfors C.
        • Holzhauser S.
        • et al.
        Incidence of human papillomavirus positive tonsillar and base of tongue carcinoma: a stabilisation of an epidemic of viral induced carcinoma?.
        Eur J Cancer. 2015; 51: 55-61
        • Antonsson A.
        • Neale R.E.
        • Boros S.
        • et al.
        Human papillomavirus status and p16(INK4A) expression in patients with mucosal squamous cell carcinoma of the head and neck in Queensland, Australia.
        Cancer Epidemiol. 2015; 39: 174-181
        • Chung C.H.
        • Zhang Q.
        • Kong C.S.
        • et al.
        P16 protein expression and human papillomavirus status as prognostic biomarkers of non oropharyngeal head and neck squamous cell carcinoma.
        J Clin Oncol. 2014; 32: 3930-3938
        • Thomas J.
        • Primeaux T.
        Is p16 immunohistochemistry a more cost-effective method for identification of human papilloma virus-associated head and neck squamous cell carcinoma?.
        Ann Diagn Pathol. 2012; 16: 91-99
        • Lassen P.
        • Eriksen J.
        • Krogdahl A.
        • et al.
        The influence of HPV-associated p16-expression on accelerated fractionated radiotherapy in head and neck cancer: evaluation of the randomised DAHANCA 6&7 trial.
        Radiother Oncol. 2011; 100: 49-55