10-year oncological outcomes of EBRT versus HIFU for stage II prostate cancer: a multicenter Chang Gung research database (CGRD) study with inverse-probability-of-treatment weighting (IPTW) analysis.

Background: To evaluate oncological outcome of external beam radiation therapy(EBRT) versus high-intensity focused ultrasound (HIFU) in patients with stage II prostate cancer.

Materials and methods: We retrospectively reviewed patients with stage II prostate cancer from the Chang Gung Research Database spanning the years 2005 to 2022. Inverse probability of treatment weighting (IPTW) method was performed to achieve baseline equivalence. Oncology outcomes including overall survival (OS) and cancer specific survival (CSS) were assessed using Kaplan-Meier curves before and after IPTW adjustment. Subgroup analysis of stage IIa, IIb, and IIc were also conducted. We use cox proportional hazards analyses to further evaluate the association between treatment and survival outcomes.

Results: Total of 176 EBRT and 244 HIFU procedures were identified. EBRT group has higher overall mortality (9.2% compared to 16.7% after IPTW; standardized difference 0.224) and cancer specific mortality (5.4% compared to 9.2% after IPTW; standardized difference 0.144) after IPTW adjustment. An overall survival benefit is observed in the HIFU group for all stage II prostate cancer cases, with a particularly significant advantage in the stage IIa subgroup after IPTW adjustment (p = 0.032). Although the cancer-specific survival benefit slightly favors the HIFU stage IIa subgroup after IPTW adjustment, it does not reach statistical significance (p = 0.069). EBRT is associated with significantly worse OS compared to HIFU across univariate, multivariate, and IPTW-adjusted Cox regression models, with hazard ratios ranging from 2.03 to 2.63 (all p 0.05). However, for CSS, a significant difference was found only in the univariate model (HR = 2.38, p = 0.032), and this association was not maintained after adjustment.

Conclusions: HIFU demonstrates non-inferior overall survival and cancer specific survival compared to EBRT in patients with stage II prostate cancer, particularly in the stage IIa subgroup after more than 10 years of follow-up. Further randomized prospective studies are needed to evaluate the oncological outcomes of different prostate cancer treatment modalities.