No survival benefit with adjuvant chemotherapy in nonserous stage IB grade 2 epithelial ovarian cancer

Abstract

Objectives: Data on the utility of adjuvant chemotherapy in patients with stage IB grade 2 epithelial ovarian cancer (EOC) are scant. Because serous histology is now reported as low- or high-grade, without an intermediate grade, this study explored the use of adjuvant chemotherapy in mucinous or endometrioid ovarian cancer. Current National Comprehensive Cancer Network guidelines state that chemotherapy is optional. We sought to evaluate the efficacy of chemotherapy and to identify factors that may predict survival in this population. Methods: The National Cancer Data Base was queried for all stage IB grade 2 EOC patients from 1998 to 2012. Only patients with mucinous or endometrioid histology and nodal dissection were analyzed. Χ2 test, logistic regression analysis, log-rank test and multivariable Cox proportional regression were conducted to determine factors associated with utilization of chemotherapy and survival. Results: A total of 227,499 patients had EOC during this period. Of these patients, 541 had stage IB grade 2 disease, with 401 having a nodal dissection. There were 226 endometrioid histology and 42 mucinous cases, for a total of 268 patients who were included. Chemotherapy was given in 60% of cases, with the majority (97%) receiving multiagent chemotherapy. There were no factors associated with the utilization of chemotherapy including histology, tumor size, age, race, facility location, or type. No association with histology or tumor size was seen with survival. Age, Charlson-Deyo Comorbidity index, and urban/rural location of patients were associated with survival on univariate analysis, but only age and location remained significant on multivariable analysis. The 5-year overall survival rates were 90% and 78% for patients who did and did not receive chemotherapy, respectively (P = .12). Conclusions: Stage IB grade 2 nonserous EOC is exceedingly rare. Even in a very large dataset, there were very few patients with this stage, grade, and histology. Because chemotherapy does not demonstrate a survival benefit in this subgroup, we recommend against adjuvant administration, given unnecessary cost and potential side effects.