Impact of changing rectal dose volume parameters over time on late rectal and urinary toxicity after high-dose intensity-modulated radiotherapy for prostate cancer: A 10-years single centre experience - Abstract

Background: External beam radiotherapy is an excellent treatment for patients with prostate cancer (PC).

Assessing long-term radiotherapy-induced toxicity is important. We evaluated the impact of implementing different rectal dose volume constraints (DVC) on late rectal and urinary toxicity.

Material and Methods: Six hundred and thirty-seven PC patients were treated with high-dose intensity-modulated radiotherapy (IMRT) in the primary (median dose of 78 Gy to the prostate) or postoperative setting (median dose of 74 (adjuvant) and 76 Gy (salvage) to the prostatic bed). Three groups were defined according to different DVC applied over time. The incidence of late rectal and urinary toxicity was evaluated. Three-year actuarial risk estimations of grade 2-3 rectal and urinary toxicity were calculated (Kaplan-Meier statistics).

Results: Median follow-up was five years. Overall, the incidence of late grade 3 and 2 rectal toxicity was 1% and 11%. The calculated three-year actuarial risk of developing late grade ≥ 2 rectal toxicity decreased from 16% to 7% and 5% for patients in Group 1, Group 2 and Group 3, respectively (p < 0.001). Respectively, 17 (4%) and 98 (24%) patients developed grade 3 and 2 late urinary toxicity in the primary setting. In the postoperative setting, 15 (6%) and 62 (26%) patients developed grade 3 and 2 urinary toxicity, respectively. The three-year actuarial risk of developing late ≥ grade 2 urinary toxicity in primary- and postoperative-treated patients was 22% and 23%, respectively. This was not significantly different between the three groups.

Conclusion: The majority of patients developed no or only moderate rectal toxicity after high-dose IMRT for PC. Implementing different rectal DVC resulted in a significant decrease of late rectal toxicity without affecting urinary toxicity.

Written by:
Fonteyne V, Sadeghi S, Ost P, Vanpachtenbeke F, Vuye P, Lumen N, De Meerleer G.   Are you the author?
Ghent University Hospital, Department of Radiation Oncology and Experimental Cancer Research, Belgium.

Reference: Acta Oncol. 2014 Nov 11:1-8.
doi: 10.3109/0284186X.2014.974826

PubMed Abstract
PMID: 25387271 Prostate Cancer Section