Objective To assess the impact of adjuvant chemotherapy on survival in patients with surgical stage I ovarian clear cell carcinoma (OCCC).

Data collection and analysis of surgical stage I OCCC patients treated at two tertiary cancer centers was performed. Descriptive statistics, univariate and multivariable analyses and Kaplan-Meier survival probability estimates were completed.

Sixty stage I OCCC patients who underwent comprehensive surgical staging were identified. 29 patients received adjuvant chemotherapy and 31 did not. Median follow-up was 4.96 (0.4-16.4) years. The 5-year disease specific survival (DSS) was 84.2%: 95% for stage IA and 76% for stage IB+IC (p=0.16). There were 11 disease specific deaths: 7 in the no adjuvant chemotherapy group (NACG) and 4 in the adjuvant chemotherapy group (ACG). 5-year DSS was 84.2%: 74% in NACG and 93% in ACG, (p=0.13). Seventeen patients recurred: 11 in NACG and 6 in ACG (p=0.2). None of the 21 patients with stage I known negative cytology recurred. 5-year PFS was 74%: 58% in NACG and 86% in ACG (p=0.035). On univariate analysis, no-adjuvant chemotherapy and positive cytology were poor prognostic factors for PFS: HR=2.36, p=0.04 and HR=3.1, p=0.027, respectively. After adjusting for positive cytology, no-adjuvant chemotherapy was still found to significantly correlate with a worse PFS (HR=4, p=0.01).

Our data supports the use of adjuvant chemotherapy for surgical stage I OCCC. As no patients in our cohort with surgical stage I known negative cytology recurred, more research on the benefit of adjuvant chemotherapy in this group is warranted.