Partial prostate treatment with MRI-guided brachytherapy may lead to poor outcomes long-term among patients with intermediate-risk prostate cancer, according to a study published in Cancer.1
Brachytherapy has been associated with favorable outcomes among patients with prostate cancer, but there are significant challenges in delivering adequate doses of radiation to the entire gland while avoiding the subsequent toxicities. Previous studies have shown that partial brachytherapy — a potential method that could reduce toxicity — leads to suboptimal biochemical disease control in intermediate-risk disease, but its impact on metastasis and mortality is unclear.
For this retrospective study, researchers evaluated the outcomes of 354 men who underwent MRI-guided partial prostate brachytherapy. Patients had clinical T1c, Gleason grade ≤3+4 disease, and a prostate-specific antigen (PSA) level of <15 ng/mL. The authors calculated the cumulative incidence of prostate cancer-specific mortality (PCSM) and distant metastasis in patients that were considered very low-risk, low-risk, and intermediate-risk per National Comprehensive Cancer Network (NCCN) guidelines. The median follow-up was 8.6 years.
Results showed that after a median of 11.0 years, 22 patients developed metastasis.
The 12-year PCSM estimates was 1.6% (95% CI, 0.1-7.6) and 1.4% (95% CI, 0.1-6.8) among very low-risk and low-risk patients respectively, but increased substantially to 8.2% (95% CI, 1.9-20.7) among patients with intermediate-risk disease.
The 12-year metastasis rates were 0.8% (95% CI, 0.1-4.4), 8.7% (95% CI, 3.4-17.2), and 15.7% (95% CI, 5.7-30.2), among patients with very low-risk, low-risk, and intermediate-risk disease, respectively.
Upon multivariate analysis, only low- (hazard ratio [HR], 6.34; 95% CI, 1.18-34.06; P = .03) and intermediate-risk (HR, 6.98; 95% CI, 1.23-39.73; P = .03) NCCN categories were significantly associated with time to metastasis.
The authors concluded that “partial prostate treatment with brachytherapy may be associated with higher rates of distant metastasis and PCSM for patients with intermediate-risk disease after long-term follow-up. Treatment of less than the full gland may not be appropriate for this cohort.”
- King MT, Nguyen PL, Boldbaatar N, et al. Long-term outcomes of partial prostate treatment with magnetic resonance imaging-guided brachytherapy for patients with favorable-risk prostate cancer [published online July 5, 2018]. doi: 10.1002/cncr.31568