Toxicity following high-dose three-dimensional conformal and intensity-modulated radiation therapy for clinically localized prostate cancer

Objectives. To report the toxicity profile of patients treated with three-d imensional conformal radiation therapy (3D-CRT) or intensity-modulated radi ation therapy (IMRT) receiving doses of 82 Cy or more to portions of their prostate. Methods. Forty-four patients treated with radiation therapy for prostate ca ncer between June 1992 and August 1998 at the University of California, San Francisco received a maximal dose within the target volume (Dmax) of 82 Gy or more. Eighteen patients were boosted selectively to a limited portion o f their prostate using IMRT, whereas 26 patients were treated with 3D-CRT a nd had unselected "hot spots" within their prostate. The Radiation Therapy Oncology Group (RTOG) acute and late toxicity scales were used to score gas trointestinal (GI) and genitourinary (GU) morbidity. Results. Median follow-up and Dmax were 23.1 months (range 10.0 to 84.7) an d 84.5 Cy (range 82.0 to 96.7), respectively. Of the patients, 59.1% and 34 .1% developed some level of acute GU and GI toxicity, respectively. One pat ient experienced grade 3 acute GI toxicity. No other grade 3 or greater acu te toxicity was observed. The 2-year actuarial rates for freedom from late GI and CU morbidity were 77.1% (95% confidence interval [CI] 60.4% to 87.5% ) and 79.5% (95% CI 62.7% to 89.3%), respectively. Although no grade 3 or g reater late GU morbidity has been observed to date, 3 patients experienced grade 3 late GI morbidity. However, these cases involved rectal bleeding an d were effectively managed with laser coagulation/fulguration. Conclusions. Doses of 82 Gy or more to a portion of the prostate gland can be tolerated with acceptable morbidity. This observation supports the conti nued investigation of IMRT as a means for improving disease control in pros tate cancer. UROLOGY 57: 102-107, 2001. (C) 2001, Elsevier Science Inc.