A Prospective Trial of Intensity-Modulated Radiation Therapy (IMRT) Incorporating a Simultaneous Integrated Boost for Prostate Cancer: Long-Term Outcomes Compared to Standard Image-guided IMRT

Abstract Objectives This report describes the long-term outcomes of a prospective trial of intensity-modulated radiotherapy (IMRT), integrating a 111-indium capromab pendetide (ProstaScint) scan-directed simultaneous-integrated boost (SIB) for localized prostate cancer. Methods and Materials Seventy-one patients with T1-T4,N0,M0 prostate cancer were enrolled, and their ProstaScint and pelvic computed tomography scans were coregistered for treatment planning. The entire prostate received 75.6Gy/42 fractions with IMRT, while regions of increased uptake on ProstaScint scans received 82Gy as a SIB. Patients with intermediate and high-risk disease also received 6 and 12 months of adjuvant hormonal therapy, respectively. Results Thirty-one low-risk, 30 intermediate-risk, and 10 high-risk patients were enrolled. The median (range) follow-up was 120 (24-150) months. The 10-year biochemical control rates were 85% for the entire cohort and 84%, 84%, and 90% for patients with low-, intermediate-, and high-risk disease, respectively. The 10-year survival rate of the entire cohort was 69%. Pretreatment prostate-specific antigen >10 ng/mL and boost volume of >10% of the prostate volume were significantly associated with poorer biochemical control and survival. The outcomes were compared to those of a cohort of 302 patients treated similarly but without the SIB and followed up for a median (range) of 91 (6-138) months. The 5- and 10-year biochemical control was 86% and 61% in patients without the SIB compared with 94% and 85% in patients in this trial who received the SIB ( P =.02). The cohort who received a SIB did not have increased toxicity. Conclusions This IMRT strategy, integrating multiple imaging modalities to administer 75.6Gy to the entire prostate with a boost dose of 82Gy, was feasible. The addition of the SIB was associated with greater biochemical control but not toxicity. Modern imaging technology can be used to locally intensify the dose to tumors and spare normal tissues, producing very favorable long-term biochemical disease control.