Comparison of three moderate fractionated schedules employed in high-dose-rate brachytherapy monotherapy for clinically localized prostate cancer. Issue 2 (November 2018) - Yamazaki, Hideya
Highlights: A long-term retrospective data for three frequently used HDR-BT monotherapy schedules. All HDR-BT monotherapy schedules showed excellent outcome in biochemical control. Higher BED correlated with higher but acceptable genitourinary toxicity. Abstract: Background: Herein, we report the outcomes of 3 schedules of high-dose-rate interstitial brachytherapy (HDR-BT) monotherapy for localized prostate cancer. Patients and methods: A total of 347 patients were treated with 45.5 Gy/7 fractions ( n = 86; 45.5 Gy arm, median follow-up time 131 months), 49 Gy/7 fractions ( n = 149; 49 Gy arm, 75.9 months), and 54 Gy/9 fractions ( n = 112; 54 Gy arm, 68 months). Results: The actuarial 5-year biochemical failure-free survival rates were 86.8%, 94.1%, and 88.5% ( p = 0.2023) for the 45.5 Gy, 49 Gy, and 54 Gy arms in the high-risk group; 90.4%, 100%, and 97.4% ( p = 0.0818) in the intermediate-risk group; and not available, 100%, and 100% in the low-risk group, respectively. The 5-year distant metastasis-free (and overall) survival rates were 94.4%, 98.2%, and 96.3% (100%, 92.8%, and 99.1%) for the 45.5 Gy, 49 Gy, and 54 Gy arms ( p = 0.5454 and p = 0.0028), respectively. At 5 years, accumulated incidence of grade ≥2 gastrointestinal toxicity was 1.2%, 2.7%, and 3.4% for the 45.5 Gy, 49 Gy, and 54 Gy arms ( p = 0.5605), respectively. For genitourinary toxicity, the 49 Gy arm showed a higher grade ≥2 toxicity of 20.5% than those observed in the 45.5 Gy (2.4%) and 54 Gy arms (10.1%). No grade 4 or 5 of either type of toxicity was detected. Conclusions: The 3 schedules showed equivocal outcomes in each risk group, with different toxicity profiles. HDR-BT monotherapy with these schedules is an acceptable treatment option for localized prostate cancer.