Primary mucinous ovarian carcinoma (MOC) is a rare histologic subtype of ovarian cancer. The benefit of adjuvant chemotherapy for patients with MOC is unclear.

Patients diagnosed with stage I mucinous ovarian cancer (MOC) between 2004 and 2015 were identified from the U.S National Cancer Database. Those with a history of another primary tumor were excluded. Factors independently associated with the receipt of chemotherapy were identified using logistic regression. Impact of chemotherapy on overall survival (OS) for patients diagnosed between 2004 and 2014 was assessed using was Kaplan-Meier curves, and compared with the log-rank test. A multivariate Cox analysis was performed to control for confounders.

We identified 4811 patients with a median age at diagnosis of 51 years (IQR: 21). Chemotherapy was administered to 1488 (30.9%) patients; 20.2% and 60.2% for those with stage IA/IB and IC respectively, p < 0.001. Stage IC, larger tumor size, and high tumor grade, were associated with the receipt of chemotherapy. There was no difference in OS between patients who did (n = 1322) and did not (n = 2920) receive chemotherapy, p = 0.17; 5-year OS rate was 86.8% vs 89.7%, respectively. No difference was noted following stratification by substage (p = 0.46 for IA/IB and p = 0.11 for IC). After controlling for substage, patient age, type of insurance, tumor grade, performance of lymphadenectomy and the presence of co-morbidities, the administration of chemotherapy was not associated with better survival (HR:1.18, 95% CI: 0.85, 1.64).

In a large cohort of patients with stage I MOC, receiving chemotherapy was not associated with a survival benefit.