Prostate cancer radiotherapy| Volume 123, ISSUE 3, P478-482, June 2017

Download started.


Stereotactic ablative radiotherapy in the treatment of low and intermediate risk prostate cancer: Is there an optimal dose?



      To investigate if stereotactic ablative radiotherapy (SABR) dose is associated with PSA at 3 years (PSA3y) in the treatment of localized prostate cancer and to explore predictors of late genitourinary (GU) toxicity.

      Materials and methods

      Three prospective trials of SABR were undertaken at our institution: 1) 35 Gy/5 fractions/29 days; 2) 40 Gy/5 fractions/29 days; 3) 40 Gy/5 fractions/11 or 29 days. PSA3y was analyzed as a continuous variable. Toxicity was defined as the worst new toxicity and assessed using the radiation therapy oncology group (RTOG) late morbidity scheme. Univariate and multivariable regression analyses were conducted to assess the association between dose and PSA3y, and to explore predictors of late grade 2+ GU toxicity.


      Median PSA3y was 0.64 (intraquartile range (IQR): 0.41–1.12) and 0.27 (IQR: 0.12–0.55) ng/mL for patients treated with 35 and 40 Gy respectively. A dose of 40 Gy was an independent predictor of lower PSA3y on multivariable analysis (p < 0.001). Dose of 40 Gy (odds ratio (OR): 16.69, 95%CI: 5.78, 48.20, p < 0.001) and higher International Prostate Symptom Score (OR: 1.01, 95%CI: 1.04, 1.16, p = 0.001) predicted for late grade 2+ GU toxicity on multivariable logistic regression.


      This analysis suggests that higher SABR dose is associated with lower PSA3y. Strategies to allow safe SABR dose escalation should be further investigated.


      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


      Subscribe to Radiotherapy and Oncology
      Already a print subscriber? Claim online access
      Already an online subscriber? Sign in
      Institutional Access: Sign in to ScienceDirect


        • Viani G.A.
        • Stefano E.J.
        • Afonso S.L.
        Higher-than-conventional radiation doses in localized prostate cancer treatment: a meta-analysis of randomized, controlled trials.
        Int J Radiat Oncol Biol Phys. 2009; 74: 1405-1418
        • Zelefsky M.J.
        • Yamada Y.
        • Fuks Z.
        • et al.
        Long-term results of conformal radiotherapy for prostate cancer: impact of dose escalation on biochemical tumor control and distant metastases-free survival outcomes.
        Int J Radiat Oncol Biol Phys. 2008; 71: 1028-1033
        • Loblaw A.
        • Cheung P.
        • D’Alimonte L.
        • et al.
        Prostate stereotactic ablative body radiotherapy using a standard linear accelerator: toxicity, biochemical, and pathological outcomes.
        Radiother Oncol. 2013; 107: 153-158
        • Tan T.-J.
        • Siva S.
        • Foroudi F.
        • Gill S.
        Stereotactic body radiotherapy for primary prostate cancer: a systematic review.
        J Med Imaging Radiat Oncol. 2014; 58: 601-611
        • King C.R.
        • Brooks J.D.
        • Gill H.
        • Presti J.C.
        Long-term outcomes from a prospective trial of stereotactic body radiotherapy for low-risk prostate cancer.
        Int J Radiat Oncol Biol Phys. 2012; 82: 877-882
      1. ASTRO Model Policies.; 2012.

        • Katz A.J.
        • Kang J.
        Quality of life and toxicity after sbrt for organ-confined prostate cancer, a 7-year study.
        Front Oncol. 2014; 4: 2-7
        • Musunuru H.B.
        • Quon H.
        • Davidson M.
        • et al.
        Dose-escalation of five-fraction SABR in prostate cancer: toxicity comparison of two prospective trials.
        Radiother Oncol. 2016; 118: 112-117
        • Katz A.J.
        • Kang J.
        Stereotactic body radiotherapy as treatment for organ confined low and intermediate risk prostate carcinoma, an eight year study.
        Radiat Oncol. 2014; 4: 1-6
        • Cavanaugh S.X.
        • Kupelian P.A.
        • Fuller C.D.
        • et al.
        Early prostate-specific antigen (PSA) kinetics following prostate carcinoma radiotherapy: prognostic value of a time-and-PSA threshold model.
        Cancer. 2004; 101: 96-105
        • Lo A.C.
        • Morris W.J.
        • Lapointe V.
        • et al.
        Prostate-specific antigen at 4 to 5 years after low-dose-rate prostate brachytherapy is a strong predictor of disease-free survival.
        Int J Radiat Oncol Biol Phys. 2014; 88: 87-93
        • Helou J.
        • Alimonte L.D.
        • Loblaw A.
        • et al.
        High dose-rate brachytherapy boost for intermediate risk prostate cancer : long-term outcomes of two different treatment schedules and early biochemical predictors of success.
        Radiother Oncol. 2015; 115: 84-89
        • Musunuru H.B.
        • Davidson M.
        • Cheung P.
        • et al.
        Predictive parameters of symptomatic hematochezia following 5-Fraction Gantry-Based SABR in prostate cancer.
        Int J Radiat Oncol. 2016; 94: 1043-1051
        • American Joint Committee on Cancer
        AJCC Cancer Staging Handbook.
        Springer, New York, NY2010
      2. Quon HC, Ong A, Cheung P, et al. PATRIOT Trial: Randomized phase II study of prostate stereotactic body radiotherapy comparing 11 versus 29 days overall treatment time. ASCO Meet Abstr. 2015;33(7_suppl).

        • Quon H.
        • Loblaw D.A.
        • Cheung P.C.F.
        • et al.
        Intra-fraction motion during extreme hypofractionated radiotherapy of the prostate using pre- and post-treatment imaging.
        Clin Oncol. 2012; 24: 640-645
        • Bursac Z.
        • Gauss C.H.
        • Williams D.K.
        • Hosmer D.W.
        Purposeful selection of variables in logistic regression.
        Source Code Biol Med. 2008; 3: 17
        • Hou Z.
        • Li G.
        • Bai S.
        High dose versus conventional dose in external beam radiotherapy of prostate cancer: a meta-analysis of long-term follow-up.
        J Cancer Res Clin Oncol. 2014; : 1063-1071
        • Fuller D.B.
        • Naitoh J.
        • Lee C.
        • Hardy S.
        • Jin H.
        Virtual HDRSM cyberknife treatment for localized prostatic carcinoma: dosimetry comparison With HDR brachytherapy and preliminary clinical observations.
        Int J Radiat Oncol Biol Phys. 2008; 70: 1588-1597
        • Zaorsky N.G.
        • Palmer J.D.
        • Hurwitz M.D.
        • Keith S.W.
        • Dicker A.P.
        • Den R.B.
        What is the ideal radiotherapy dose to treat prostate cancer? A meta-analysis of biologically equivalent dose escalation.
        Radiother Oncol. 2015; 115: 295-300
        • King C.R.
        • Freeman D.
        • Kaplan I.
        • et al.
        Stereotactic body radiotherapy for localized prostate cancer: pooled analysis from a multi-institutional consortium of prospective phase II trials.
        Radiother Oncol. 2013; 109: 217-221
      3. Michalski, Jeff M. Moughan, Jennifer. Purdy, James. Bosh W. Michalski 2015. 2015:suppl 7; abstr 4.

        • Dearnaley D.P.
        • Sydes M.R.
        • Graham J.D.
        • et al.
        Escalated-dose versus standard-dose conformal radiotherapy in prostate cancer: first results from the MRC RT01 randomised controlled trial.
        Lancet Oncol. 2007; 8: 475-487
        • Al-Mamgani A.
        • van Putten W.L.J.
        • Heemsbergen W.D.
        • et al.
        Update of dutch multicenter dose-escalation trial of radiotherapy for localized prostate cancer.
        Int J Radiat Oncol Biol Phys. 2008; 72: 980-988
        • Mantz C.
        A phase II trial of stereotactic ablative body radiotherapy for low-risk prostate cancer using a non-robotic linear accelerator and real-time target tracking: report of toxicity, quality of life, and disease control outcomes with 5-year minimum follow-up.
        Front Oncol. 2014; 4: 279