Might definitive local therapy of the primary tumor improve the survival benefits of metastatic prostate cancer?-evidence from a meta-analysis

Background: With the successful application of local therapy (LT) of the primary tumor in other metastatic disease and the demonstration of their better survival benefits, the traditionally seldom involved role of LT for metastatic prostate cancer (mPCa) had gained a lot of interest. Hence, this meta-analysis was conducted to clarify its efficacy in mPCa. Methods: A comprehensive search of major databases (PubMed, EMBASE and Web of Science) was conducted for eligible studies, up to May 2019. The pooled hazard ratio (HR) with 95% confidence interval (CI) was utilized to evaluate the efficacy of LT for mPCa. Results: A total of 12 eligible studies with 78,864 participants, containing 28 different comparisons were ultimately enrolled in this article. Our results showed that LT involving radical prostatectomy (RP) or radiation therapy (RT) for mPCa was related to enhanced overall survival (OS) (pooled HR =0.53, 95% CI: 0.47 to 0.61, I-2=59.7%, P=0.015), decreased cancer-specific mortality (CSM) (pooled HR =0.42, 95% CI: 0.34 to 0.51, I-2=63.1%, P=0.004) and lower all-cause mortality (ACM) (pooled HR =0.37, 95% CI: 0.31 to 0.45, I-2=49.4%, P=0.115), compared with no local therapy (NLT). In subsequent stratified analysis, RP or RT was respectively linked to longer OS (pooled HR =0.49, 95% CI: 0.44 to 0.54, I-2=0.0%, P=0.741; pooled HR =0.64, 95% CI: 0.56 to 0.72, I-2=15.4%, P=0.306), lower CSM (pooled HR =0.37, 95% CI: 0.29 to 0.46, I-2=35.2%, P=0.187; pooled HR =0.51, 95% CI: 0.42 to 0.63, I-2=27.0%, P=0.250) and decreased ACM (pooled HR =0.31, 95% CI: 0.23 to 0.40, I-2=56.4%, P=0.130; pooled HR =0.44, 95% CI: 0.34 to 0.56, I-2=0.0%, P=0.856), compared with NLT. In terms of RP vs. RT, RP was linked to a decreased CSM (pooled HR =0.59, 95% CI: 0.53 to 0.66, I-2=0.0%, P=0.653). Conclusions: In summary, our results shed light on the positive role of LT (RP or RT) for mPCa and meanwhile its feasibility and survival benefits had been demonstrated. Moreover, when compared with RT, RP showed its superiority in CSM. Upcoming prospective randomized controlled trials should be taken to validate our findings.