Utilization and outcomes of chemotherapy in women with intermediate-risk, early-stage ovarian cancer

OBJECTIVE: To examine utilization and efficacy of chemotherapy for stage I ovarian cancer. METHODS: We conducted a retrospective cohort study using the National Cancer Data Base to identify women with stage I ovarian cancer treated from 1998 to 2012. Patients were classified into three groups based on grade and stage: stage IA or IB grade 1 (low risk); stage IA or IB grade 2 (intermediate risk); and stage IA or IB grade 3 or any stage IC (high risk). Multivariable models were developed to examine predictors of chemotherapy use and survival. RESULTS: We identified 21,758 patients including 4,196 (19.3%) low-risk, 3,777 (17.4%) intermediate-risk, and 13,785 (63.4%) high-risk women. The median follow-up of the cohort was 63.9 months. Use of chemotherapy within the groups was 15.5%, 39.5%, and 69.8%, respectively (P<.001). Among low-risk patients, chemotherapy was not associated with a change in survival (adjusted hazard ratio [HR] 1.10, 95% confidence interval [CI] 0.85-1.42), whereas chemotherapy was associated with reduced mortality for high-risk patients (adjusted HR 0.78, 95% CI 0.71-0.85). For intermediate-risk patients (stage IA-IB grade 2), chemotherapy was associated with a 26% reduction in mortality (adjusted HR 0.74, 95% CI 0.62-0.89). The association between chemotherapy and improved survival among intermediate-risk patients remained significant when limited to patients who underwent staging lymphadenectomy (adjusted HR 0.77, 95% CI 0.62-0.97). CONCLUSION: There is widespread variation in the patterns of care for early-stage ovarian cancer. Chemotherapy was associated with improved survival for stage IA-IB grade 2 patients.