Age comparisons of endometrial cancer clinicopathology and treatment in the United States Military Health System

Abstract: INTRODUCTION: Endometrial cancer incidence is rising in the United States, including among women younger than 50 years, raising concern for women serving on active duty, retirees, and their dependents. Age-related differences in clinicopathologic features and treatment have been documented in the general U.S. population and the differences may be influenced by access to care. We aimed to study clinicopathologic and treatment features of women within the Department of War (DoW) Military Health System (MHS) to better understand age-related differences in tumor characteristics, surgical management, and adjuvant therapy by age in this universal access setting. MATERIALS AND METHODS: We conducted a retrospective cohort study using the Military Cancer Epidemiology (MilCanEpi) database, which links the DoW cancer registry and medical claims data. Women diagnosed with endometrial cancer from 2001 to 2014 who underwent hysterectomy within 6 months of diagnosis were included. Modified Poisson regression was used to estimate adjusted risk ratios (ARRs) for advanced tumor stage (II-IV vs. I), aggressive histological subtypes (high-grade endometrioid endometrial carcinoma [EEC] or non-EEC vs. low-grade EEC), surgical approach, and adjuvant therapy (chemotherapy or radiation) by age group: 18-49, 50-64, and ≥65 years. RESULTS: Among 1,223 patients, 16% were aged 18-49, 61% aged 50-64, and 23% aged ≥65. Compared with women aged 50-64, those aged 18-49 were less likely to have aggressive histologic subtypes (ARR=0.65; 95% CI=0.44-0.96), while those aged ≥65 were at higher risk for more aggressive histologic subtypes (ARR=1.54; 95% CI=1.25-1.90). No significant age-related differences were observed in tumor stage, time to surgery, surgical approach, or lymphadenectomy. Among patients with aggressive histologic subtypes (n=287), receipt of adjuvant therapy did not differ significantly by age (18-49 years: ARR=0.84, 95% CI=0.58-1.21; ≥65 years: ARR=0.92, 95% CI=0.78-1.08) relative to women aged 50-64 years at diagnosis. CONCLUSIONS: Within the MHS, age-related differences in endometrial cancer were confined to tumor histology, with younger women less likely and older women more likely to present with aggressive subtypes. This is consistent with that reported in the general U.S. population. Importantly, no age-related differences were observed in surgical management or receipt of adjuvant therapy when adjusted for tumor features. This may suggest the role of healthcare access in mitigating age-related treatment gaps observed in the general population.