Acute morbidity reduction using 3DCRT for prostate carcinoma: A randomizedstudy

Purpose: To study the effects on gastrointestinal and urological acute morb idity, a randomized toxicity study, comparing conventional and three-dimens ional conformal radiotherapy (3DCRT) for prostate carcinoma was performed. To reveal possible volume effects, related to the observed toxicity, dose-v olume histograms (DVHs) were used. Methods and Materials: From June 1994 to March 1996, 266 patients with pros tate carcinoma, stage T1-4N0M0 were enrolled in the study. All patients wer e treated to a dose of 66 Gy (ICRU), using the same planning procedure, tre atment technique, linear accelerator, and portal imaging procedure. However , patients in the conventional treatment arm were treated with rectangular, open fields, whereas conformal radiotherapy was performed with conformally shaped fields using a multileaf collimator. All treatment plans were made with a 3D planning system. The planning target volume (PTV) was defined tea be the gross target volume (GTV) + 15 mm. Acute toxicity was evaluated usi ng the EORTC/RTOG morbidity scoring system. Results: Patient and tumor characteristics were equally distributed between both study groups. The maximum toxicity was 57% grade 1 and 26% grade 2 ga strointestinal toxicity; 47% grade 1, 17% grade 2, and 2% grade > 2 urologi cal toxicity. Comparing both study arms, a reduction in gastrointestinal to xicity was observed (32% and 19% grade 2 toxicity for conformal and convent ional radiotherapy, respectively; p = 0.02). Further analysis revealed a ma rked reduction in medication for anal symptoms: this accounts for a large p art of the statistical difference in gastrointestinal toxicity (18% vs. 14% [p = ns] grade 2 rectum/sigmoid toxicity and 16% vs. 8% [p < 0.0001] grade 2 anal toxicity for conventional and conformal radiotherapy, respectively) . A strong correlation between exposure of the anus and anal toxicity was f ound, which explained the difference in anal toxicity between both study ar ms. No difference in urological toxicity between both treatment arms was fo und, despite a relatively large difference in bladder DVHs. Conclusions: The reduction in gastrointestinal morbidity was mainly account ed for by reduced toxicity for anal symptoms using 3DCRT. The study did not show a statistically significant reduction in acute rectum/sigmoid and bla dder toxicity. (C) 1999 Elsevier Science Inc.