Impact of traditional Chinese medicine combined with conventional therapies on the survival of patients with metastatic prostate cancer: a retrospective observational cohort study.

Background: Traditional Chinese medicine (TCM) is incorporated into the long-term integrative management of advanced prostate cancer in China, but evidence linking treatment duration with survival remains limited. Because treatment duration accumulates during follow-up, classifying patients by their final recorded treatment duration can misallocate pre-threshold observation time and bias survival comparisons. Methods: We evaluated the association between cumulative continuous TCM treatment exceeding 6 months and all-cause mortality in a single-center retrospective cohort of 242 patients with metastatic prostate adenocarcinoma at diagnosis who received continuous TCM from diagnosis. Follow-up continued through May 1, 2024. Treatment exceeding 6 months was modeled as a time-dependent exposure in Multivariable Cox regression, with sensitivity analyses addressing an alternative threshold, disease-severity adjustment, influential observations, and loss to follow-up. Results: During follow-up, 147 deaths occurred. Median overall survival was 53.0 months (95% confidence interval [CI], 44.0-61.0), with 3- and 5-year survival rates of 64.0% and 43.4%, respectively. Cumulative continuous TCM treatment exceeding 6 months was associated with a lower average hazard of all-cause mortality (adjusted hazard ratio [HR], 0.269; 95% CI, 0.186-0.389; P < 0.001). The association attenuated over time: adjusted HRs at 1, 2, 3, and 5 years were 0.098, 0.192, 0.286, and 0.471, respectively. Sensitivity analyses yielded estimates in the same direction. Conclusion: These findings define a duration-survival association among TCM users and support prospective, multicenter evaluation using detailed longitudinal treatment records.