Metastatic small cell carcinoma of the prostate: Population-based analysis of patient characteristics and treatment paradigms

IntroductionSmall cell carcinoma of the prostate is a rare malignancy comprising<1% of prostate cancers. Little is known about population-based treatment patterns for metastatic small cell carcinoma of the prostate. We evaluated clinical characteristics, treatment patterns, and survival outcomes.MethodsUsing the National Cancer Database, we identified patients between 1998 and 2011 diagnosed with pure small cell carcinoma of the prostate as their only malignancy who presented with nodal involvement or distant metastasis.ResultsTreatment information was available for 379 patients. Of them, 122 (32.5%) underwent chemotherapy (CT) alone, 25 (6.7%) received hormonal therapy (androgen-deprivation therapy) alone, 10 (2.7%) underwent radiation therapy alone, 3 (1%) underwent radical prostatectomy, and 167 (44.4%) underwent combination therapy. The 1- and 3-year survival rates were 35.3% and 4.4%, respectively. Those receiving any CT as part of their treatment had a median survival of 9.3 vs. 3.2 months for those not receiving it (P<0.001). Those receiving CT, androgen-deprivation therapy, and radiation had a median survival of 15.1 vs. 7 months for those receiving CT alone (P<0.001). On multivariable analysis (controlling for age, Charlson comorbidity index, extent of metastasis, prostate-specific antigen level, and type of treatment), older age (hazard ratio [HR] = 3.87; 95% CI: 1.41-9.34; P = 0.007) and distant metastatic disease (HR = 7.17; 95% CI: 1.62-31.8; P = 0.010) increased risk of death, whereas receipt of CT (HR = 0.15; 95% CI: 0.05-0.44; P = 0.001) decreased risk of death.ConclusionMen presenting with metastatic small cell carcinoma of the prostate have poor overall survival. Older patients and those presenting with distant metastases have an increased risk of death. It appears that patients receiving CT experience a modest survival benefit. The role of hormonal therapy in this population remains unclear.