Aims

Obesity is a risk factor for developing endometrial cancer (EC), but its impact on treatment outcome is less clear. Previous studies found higher all-cause mortality in obese EC survivors. However, patients receiving adjuvant radiation were not specifically studied. We aimed to determine if obese EC patients (body mass index [BMI] >30) have inferior survival and/or more pelvic relapse following adjuvant radiation ±chemotherapy.

Methods

Women referred for adjuvant radiation after surgery for EC between 1/2000- 12/2013 were included. Clinico-pathological, treatment and outcome data were sourced from a prospective institutional database. Cox proportional hazards regression was used to test for a relationship between BMI and overall survival (OS), adjusting for potential confounders. Patients with BMI≤30 and BMI>30 are compared for relapse site (pelvic, para-aortic, distant) by conditional logistic regression; and assessed for differences in chemotherapy-use and radiation toxicity.

Results

215 patients with 3.6 years median follow-up were identified. 105 (49%) had BMI>30. There were no significant differences in baseline disease characteristics between the BMI ≤30 and >30 groups. BMI >30 patients were less likely to undergo lymphadenectomy [39/104 (26%)] compared to the BMI ≤30 group [26/99 (38%)], p=0.085. There was no significant association between BMI and overall survival (HR 0.97, 95% CI 0.93 – 1.01, p=0.176); five-year survivals were 70% (BMI ≤30) and 78% (BMI >30). On multivariate analysis, only FIGO stage (HR 1.48, 95% CI 1.05 – 2.08, p=0.022) and tumour grade (HR 0.34, 95% CI 0.16 – 0.72, p=0.003) were significantly associated with overall survival. No association was found between BMI and progression-free survival (HR 0.99, 95% CI 0.96 – 1.02, p=0.548) or site of relapse.

Conclusions

BMI did not affect treatment outcome in this population of EC patients receiving adjuvant radiation, despite less extensive surgery in the obese. FIGO grade and tumour stage remained prognostic for survival.  Obese patients did not have a propensity for increased pelvic relapse, supporting effective local therapy delivery regardless of BMI.