A Limited-Versus-Extensive Staging Strategy for Small Cell Prostate Cancer

Introduction:Small cell prostate cancer (SCPC) is a rare histologic subtype of prostate cancer, for which the optimal staging strategy remains unclear.Method:The Surveillance, Epidemiology, and End Results database was used to analyze the incidence and outcomes of SCPC between the years 2004 through 2016. Limited-stage SCPC (LS-SCPC) was defined as SCPC without any metastasis regardless of local invasion. Extensive stage SCPC (ES-SCPC) was defined as any metastasis to lymph nodes and/or to distant organs.Result:A total of 403 SCPC patients were included in the study cohort, accounting for 0.056% of all prostate cancer cases (n=719,655). Of the 358 patients with known metastasis status, 275 (76.8%) patients had ES-SCPC, whereas 83 (23.2%) patients had LS-SCPC. LS-SCPC was associated with better overall survival (17 vs. 9 mo, P<0.001) and disease-specific survival (25 vs. 10 mo, P<0.001) compared with ES-SCPC. All LS-SCPC patients had a similar overall survival regardless of T stage. Similarly, all ES-SCPC patients had similar outcomes regardless of metastasis sites. High prostate-specific antigen (PSA) is paradoxically associated with superior outcome in both localized stage patients (PSA≥4 vs. PSA<4, 19 vs. 10 mo, P=0.002) and extensive stage patients (PSA≥20 vs. PSA<20, 13 vs. 9 mo, P=0.02). Multivariate analysis of treatment showed that chemotherapy was associated with improved survival in ES-SCPC with hazard ratio of 0.52.Conclusion:Similar to small cell lung cancer, SCPC can be staged into LS-SCPC or ES-SCPC. The binary staging system correlates well with prognosis.