Population-based Analysis of the Clinical Features of Primary Small Cell Carcinoma of the Ovary

Background: Primary small cell carcinoma of the ovary (SCCO) is rare, making prognosis and outcomes largely undefined. Patients and Methods: Using case listing session of SEER 18 (1973-2010), we examined outcomes for patients with SCCO. Analyses were conducted with SEER*Stat 8.1.2, Microsoft Excel 2007 and GraphPad Prism 6. Comparisons were made using the Chi-square test and log-rank test (Mantel-Cox) and all p-values were 2-sided. Results: One hundred and eighty-one patients with SCCO with staging information were identified with a median age of 37 (range = 10-91). Twenty-nine patients (15%) had localized, 19 (11%) regional and 133 (74%) distant disease at presentation. All patients with localized and 95% of patients with regional disease had surgery. The extent of surgery did not influence outcomes. Median overall survival (OS) varied by stage (67 months vs. 12 months vs. 9 months, p<0.001). Radiation was rarely used in localized (1 patient) or regional disease (3 patients). For comparison, 81,933 cases of SCLC were identified from the same database with a median age of 68; 8% of small cell lung cancer (SCLC) patients had localized, 29% regional and 63% distant disease. Outcomes were superior for patients with SCCO with localized disease (67 months vs. 16 months, p<0.001) but there was no clinically meaningful difference in patients with regional (12 months vs. 13 months, p=0.675) or distant disease (9 months vs. 7 months, p<0.001). Conclusion: SCCO presents at a younger age than SCLC but has a similar stage distribution. Patients with localized SCCO have a more favorable prognosis than patients with SCLC but patients with regional and distant disease have similar outcomes.