Determine if patients with stage IIIC endometrioid endometrial cancer who receive external beam radiation (EBRT) in addition to adjuvant chemotherapy with or without vaginal brachytherapy have a greater chance of surviving.

The National Cancer Database was used to identify patients diagnosed between 2010 and 2015 with apparent early-stage endometrioid adenocarcinoma, without a prior history of another tumor, who had hysterectomy with lymphadenectomy and positive lymph nodes. For further investigation, those who underwent adjuvant chemotherapy (defined as receiving treatment within 6 months of surgery) and had at least one month of follow-up were chosen. The log-rank test was used to assess overall survival between patients who received EBRT within six months after surgery and those who did not. In order to account for confounders, a Cox model was also created.

There were 3,116 patients altogether, of whom 1,458 (46.8%) underwent chemotherapy without EBRT, and 1,658 (53.2%). Tumor grade, size, endocervical spread, and lymph-vascular penetration were equivalent across the two groups regarding pathologic features. About P=0.001 showed that patients who got external beam radiation fared better than those who did not; the 5-year overall survival rates were 83.1% and 77.9%, respectively. After comorbidities, insurance status, tumor size, grade, endocervical invasion, and lymphovascular invasion were taken into account, the inclusion of EBRT was linked to a survival advantage (HR: 0.75, 95% CI: 0.62, 0.91).

The addition of external beam radiation to adjuvant chemotherapy may be related to a survival advantage for patients with endometrioid adenocarcinoma that has spread to their lymph nodes.