Introduction

Neuroendocrine carcinoma of the prostate (NEPC) is an uncommon histologic type, described only in few reports. The present study provides population-based incidence rates and oncological outcomes for NEPC.

Methods

The current analysis relied on a total of 309 individuals diagnosed with histologically-confirmed NEPC between 2004 and 2013 within the Surveillance, Epidemiology, and End Results (SEER) registries. Patients with unknown metastatic stage (Mx) were not considered. Age-adjusted incidence rates (AAI) was calculated after correction according to the 2000 United States standard population and plotted according to the year of diagnosis. Temporal trend for AAI was quantified using the annual percentage change (APC) with the least squares linear regression. Among NEPC individuals, those with small cell carcinoma (SCC) histological subtype were identified and stratification was performed according to SCC vs. non-SCC (NSCC) histological variant. Kaplan-Meier estimate plots described overall survival (OS) in the entire cohort, as well as after stratification according to metastatic status and histological subtype.

Results

A total of 309 patients harboured NEPC. Of those, 60.2% (n=186) harboured SCC. A total of 64.1% (n=198) harboured metastatic disease. Annual AAI rates ranged from 0.23/1,000,000 person years in 2004 to 0.40/1,000,000 person years in 2013, with a statistically-significant increase over the study period (p=0.02; Figure 1). Median survival in the overall population was 10 months, with a difference between SCC and NSCC that only bordered statistical significance (10 vs. 12 months; p=0.05). Median survival was 13 versus 8 months for M0 vs. M1 disease (p<0.001). In SCC individuals, median survival was 12 versus 8 months for M0 vs. M1 disease (p<0.001). In NSCC, median survival was 15 vs. 9 months for M0 vs. M1 disease (p=0.01)

Conclusions

Despite a small but statistically-significant increase in NEPC incidence, it still represents a very rare entity. Most cases are represented by SCC. Survival is very poor, regardless of histological variant. While metastatic status at diagnosis confers worse survival rates, the absolute survival difference remains negligible.

Funding

none