National trends, outcomes, and costs of radiation therapy in the management of low- and high-intermediate risk endometrial cancer.

OBJECTIVE: To assess treatment patterns, outcomes, and costs for women with low-(LIR) and high-intermediate risk endometrial cancer (HIR) who are treated with and without adjuvant radiotherapy.

METHODS: All patients with stage I endometrioid endometrial cancer who underwent surgery from 2000 to 2011 were identified from the SEER-Medicare database. LIR was defined as G1-2 tumors with <50% myometrial invasion or G3 with no invasion. HIR was defined as G1-2 tumors with ≥50% or G3 with <50% invasion. Patients were categorized according to whether they received adjuvant radiotherapy (vaginal brachytherapy [VBT], external beam radiotherapy [EBRT], or both) or no radiotherapy. Outcomes were analyzed and compared (primary outcome was overall survival).

RESULTS: 10,842 patients met inclusion criteria. In the LIR group (n = 7609), there was no difference in 10-year overall survival between patients who received radiotherapy and those who did not (67% vs 65%, adjusted HR 0.95, 95% CI 0.81-1.11). In the HIR group (n = 3233), patients who underwent radiotherapy had a significant increase in survival (60% vs 47%, aHR 0.75, 95% CI 0.67-0.85). Radiotherapy was associated with increased costs compared to surgery alone ($26,585 vs $16,712, p < .001). Costs for patients receiving VBT, EBRT, and concurrent VBT/EBRT were $24,044, $27,512, and $31,564, respectively (p < .001). Radiotherapy was associated with an increased risk of gastrointestinal (7 vs 4%), genitourinary (2 vs 1%), and hematologic (16 vs 12%) complications (p < .001).

CONCLUSIONS: Radiotherapy was associated with improved survival in women with HIR, but not in LIR. It also had increased costs and a higher morbidity risk. Consideration of observation without radiotherapy in LIR may be reasonable.