Real-world experience managing unresectable or metastatic small cell carcinoma of the prostate.

Introduction: Unresectable and metastatic small cell carcinoma of the prostate (SCPC) is a rare and aggressive disease that is under-represented in clinical trials. We carried out a retrospective chart review of metastatic or unresectable SCPC patients at British Columbia (BC) Cancer centers, studying diagnosis and treatment patterns.
Methods: Drug-dispensing records from the six BC Cancer centers were obtained from 2002-2017. For each patient, information was collected on baseline information prior to therapy and for each line of treatment. Treatments at each line were compared regarding time to progression and overall survival by Kaplan-Meier curves.
Results: Forty-one patients received treatment; 65.6% had metastatic disease and 61% had pure small cell carcinoma. Median time from treatment to death was 10 months (95% confidence interval [CI] 6-16). Patients with initially prostate-confined disease had a better median overall survival (mOS) of 21 months (95% CI 13-34) compared to those with initially locally advanced (mOS 19 months, 95% CI 5-37) and metastatic disease (mOS 8 months, 95% CI 6-10) (log-rank p=0.0364). All patients received either cisplatin- or carboplatin-based combination chemotherapy as the first-line treatment and 36.7% received second-line therapy. Time to second-line therapy was eight months for those who presented with metastatic SCPC, compared to 13 months for those with initial non-metastatic SCPC.
Conclusions: This single-province, multi-institution cohort reports data on unresectable and metastatic SCPC and highlights the poor prognosis of this rare disease entity.