(P070) High-Risk Prostate Adenocarcinoma Treated With Whole-Pelvis Radiotherapy HDR Brachytherapy Boost Results in Very High Disease-Specific Survival

April 30, 2015

Pelvic radiotherapy followed by HDR brachytherapy boost is an effective treatment for high-risk prostate cancer. It provides excellent long-term disease control and very low rates of severe (grade ≥ 3) toxicity when delivered in two or three fractions.

Julian Johnson, MD, Mack Roach, MD, Alexander Gottschalk, MD, PhD, Adam Cunha, PhD, Zachary Seymour, David Raleigh, MD, PhD, Katsuto Shinohara, MD, I-Chow Hsu, MD, Albert Chang, MD, PhD; University of California, San Francisco

PURPOSE/OBJECTIVES: To report the long-term clinical outcomes of patients with high-risk adenocarcinoma of the prostate treated with pelvic radiotherapy followed by inverse planned, template-free high-dose-rate (HDR) brachytherapy boost treated at a single institution.

MATERIALS AND METHODS: A total of 115 patients with high-risk prostate cancer (≥ cT3, Gleason score [GS] 8–10, or PSA ≥ 20 ng/mL) treated between July 1997 and November 2005 were included in this study. All patients underwent whole-pelvis external beam radiotherapy to 45 Gy followed by HDR brachytherapy boost. HDR brachytherapy boost consisted of 6 Gy × 3 (38 patients) or 9.5 Gy × 2 (77 patients) to the prostate and seminal vesicles. A total of 47%, 48%, and 5% of patients received long-term (> 18 mo), short-term (4–6 mo), or no androgen deprivation therapy, respectively.

RESULTS: The median age at diagnosis was 64.8 years; 50 (43%), 90 (78.2%), and 24 (20.8%) patients were diagnosed with GS 8–10, cT3 disease, and PSA ≥ 20 ng/mL, respectively. Mean PSA was 14.94 ng/mL (range: 0.21–99.3 ng/mL). Further, 21 patients (18.1%) had seminal vesicle invasion, and 42 patients (37%) had at least two high-risk features. With a median follow-up time of 94 months, 5- and 10- year biochemical-free survival, as defined by the Phoenix definition, was 90% and 73%, respectively. At 10 years, four patients failed locally, as determined by biopsy, for a local control rate of 94%. The 5- and 10-year distant metastasis-free survival rates were 97% and 87%, respectively. The 5- and 10-year disease-specific survival rates were 100% and 92.5%, respectively. Six secondary malignancies (bladder carcinoma 1 year posttreatment, colon, lung, melanoma, and hepatocellular carcinoma) developed. One patient developed grade 3 ureteral stricture that caused hydronephrosis and required stent placement. There were no other grade ≥ 3 genitourinary or gastrointestinal toxicities.

CONCLUSION: Pelvic radiotherapy followed by HDR brachytherapy boost is an effective treatment for high-risk prostate cancer. It provides excellent long-term disease control and very low rates of severe (grade ≥ 3) toxicity when delivered in two or three fractions.

Proceedings of the 97th Annual Meeting of the American Radium Society- americanradiumsociety.org