Risk of All-Cause and Prostate Cancer–Specific Mortality After Brachytherapy in Men With Small Prostate Size

Background Brachytherapy for prostate cancer can be technically challenging in men with small prostates (≤20 cc), but it is unknown whether their outcomes are different than those of men with larger prostates. Methods and Materials We studied 6,416 men treated with brachytherapy in one of 21 community-based practices. Cox regression and Fine and Gray's regression were used to determine whether volume ≤20 cc was associated with a higher risk of all-cause mortality (ACM) or prostate cancer–specific mortality (PCSM), respectively, after adjustment for other known prognostic factors. Results 443 patients (6.9%) had a prostate volume ≤20 cc. After a median follow-up of 2.91 years (interquartile range, 1.06–4.79), volume ≤20 cc was associated with a significantly higher risk of ACM (adjusted hazard ratio = 1.33 [95% CI 1.08–1.65], p = 0.0085) with 3-year estimates of ACM for ≤20 cc vs. >20 cc of 13.0% vs. 6.9% ( p = 0.028). Only 23 men (0.36%) have died of prostate cancer, and no difference was seen in PCSM by volume ( p = 0.4). Conclusion Men with small prostates at the time of implant had a 33% higher risk of ACM, and the underlying cause of this remains uncertain. No increase in PCSM was observed in men with volume ≤20cc, suggesting that a small prostate should not in itself be a contraindication for brachytherapy, but inasmuch as absolute rates of PCSM were small, further follow-up will be needed to confirm this finding.