Adaptive radiation therapy for breast IMRT-simultaneously integrated boost: Three-year clinical experience

Hurkmans, Coen W.; Dijckmans, Ingrid; Reijnen, Miranda; van der Leer, Jorien; van Vliet-Vroegindeweij, Corine; van der Sangen, Maurice

doi:10.1016/j.radonc.2011.12.014

« Previous Next »Radiotherapy & Oncology
Volume 103, Issue 2 , Pages 183-187, May 2012

Adaptive radiation therapy for breast IMRT-simultaneously integrated boost: Three-year clinical experience

Coen W. Hurkmans
- Department of Radiation Oncology, Catharina Hospital, Eindhoven, The Netherlands
- Corresponding author. Address: Department of Radiation Oncology, Catharina Hospital, Michelangelolaan 1, Eindhoven, The Netherlands.
Ingrid Dijckmans
- Department of Radiation Oncology, Catharina Hospital, Eindhoven, The Netherlands
Miranda Reijnen
- Department of Radiation Oncology, Catharina Hospital, Eindhoven, The Netherlands
Jorien van der Leer
- Department of Radiation Oncology, Catharina Hospital, Eindhoven, The Netherlands
Corine van Vliet-Vroegindeweij
- Department of Radiation Oncology, The Netherlands Cancer Institute – Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands
Maurice van der Sangen
- Department of Radiation Oncology, Catharina Hospital, Eindhoven, The Netherlands

Received 29 March 2011; received in revised form 15 December 2011; accepted 19 December 2011. published online 27 January 2012.

Abstract

Purpose

It has been shown that seroma volumes decrease during breast conserving radiotherapy in a significant percentage of patients. We report on our experience with an adaptive radiation therapy (ART) strategy involving rescanning and replanning patients to take this reduction into account during a course of intensity-modulated radiation therapy with simultaneously integrated boost (IMRT-SIB).

Materials

From April 2007 till December 2009, 1274 patients eligible for SIB treatment were enrolled into this protocol. Patients for which the time between the initial planning CT (CT₁) and lumpectomy was less than 30days and who had an initial seroma volume >30cm³ were rescanned at day 10 of treatment (CT₂) and replanned when significant changes were observed by the radiation oncologist. Patients received 28 fractions of 1.81Gy to the breast and 2.30Gy to the boost volume.

Results

Nine percent (n=113) of the 1274 patients enrolled met the criteria and were rescanned. Of this group, 77% (n=87) of treatment plans were adapted. Time between surgery and CT₁ (20days versus 20days for adapted and non-adapted plans, p=0.89) and time between CT₁ and CT₂ (21days versus 22days for adapted and non-adapted plans, p=0.43) revealed no procedural differences which might have biased our results. In the adapted plans, seroma decreased significantly from 60 to 27cm³ (p<0.001), TBV from 70 to 45cm³ (p<0.001) and PTV_boost from 277 to 220cm³ (p<0.001). The volume receiving more than 95% of the boost dose (V_{95%(total-dose)}) could be reduced by 19% (linear fit, R²=0.73) from on average 360 to 292cm³ (p<0.001). Delay in treatment and the use of a prolonged treatment schedule with different fractionation for patients with seroma could thus be prevented.

Conclusion

The adaptive radiation therapy IMRT-SIB procedure has proven to be efficient and effective, leading to a clinically significant reduction of the high dose volume. Seroma present in a subgroup of patients referred for breast radiation therapy does not hamper the introduction of highly conformal IMRT-SIB techniques.

Keywords: Breast cancer, Post-operative seroma volume change, Adaptive image guided radiation therapy, Simultaneously integrated boost, Tumor bed volume