Adjuvant chemotherapy is not associated with improved overall survival with stage I endometrioid ovarian cancer patients in a SEER cohort

The objectives of this study was to investigate the prognostic significance of adjuvant chemotherapy in early-stage endometrioid ovarian cancer (EnOC) patients, especially those with grade II stage IA and IB and grade I stage IC, that are not explicitly recommended in the current National Comprehensive Cancer Network (NCCN) guidelines. This was a retrospective cohort study based on the Surveillance, Epidemiology and End Results (SEER) database, comprising 875 cases diagnosed with stage I EnOC from 2010 to 2018, of whom 441 (50%) and 434 (50%) received and did not receive chemotherapy, respectively. The Kaplan-Meier method was used for survival analysis, and the Cox multivariate regression analysis was performed to identify independent prognostic factors. Stratified survival analysis for adjuvant chemotherapy based on the recommendations of the NCCN Guidelines in stage I EnOC patients with different substages and grades showed that in this cohort adjuvant chemotherapy did not improve the survival of any of the stage I stratified substages group (p = 0.076, HR: 0.600, 95% CI: 0.342-1.054). Age >= 60 (p = 0.000, HR: 3.609, 95% CI: 2.156-6.039) and elevated CA125 (p = 0.028, HR: 2.480, 95% CI: 1.103-5.577) were independent risk factors associated with worse survival in stage I EnOC patients. In conclusion, chemotherapy would be unnecessary for stage I EnOC patients to improve the overall survival no matter substage and grade in our cohort.