Primary radiotherapy for nonsurgically managed Stage I endometrial cancer: Utilization and impact of brachytherapy.

Objective: The National Cancer Data Base (NCDB) was analyzed to evaluate practice patterns and the impact of radiotherapy modalities for endometrial cancer treated with primary radiotherapy.

Methods: The NCDB was queried for Stage I endometrioid adenocarcinoma patients treated with primary radiotherapy without surgery from 1998 to 2006. Brachytherapy (BT) utilization factors were established using multivariable logistic regression. Log-rank and Cox proportional hazards modeling were used to assess variables impacting survival.

Results: A total of 853 patients were analyzed: 23.7%, 31.3%, and 45.0% received BT alone, external beam radiotherapy (EBRT) and BT, or EBRT alone. The BT utilization ranged from 40.5% to 51.9% over time (p=0.70). Lower utilization was associated with advanced age (≥80 years: odds ratio [OR] 0.43, 95% confidence interval [CI] 0.28-0.65, p<0.01) and facilities with volume in the bottom quartile (OR 0.44, 95% CI 0.30-0.66, p<0.01). Utilization was higher among patients living more than 30 miles from the facilities (OR 2.14, 95%CI 1.35-3.42, p<0.01). With 36-month median followup, unadjusted median survivals for EBRT dose of 30Gy or lower, EBRT dose higher than 30Gy, BT, and EBRT+BT were 12.6, 31.1, 44.6, and 57.1 months (p<0.01). After correcting for other factors, higher risk of mortality was seen with EBRT dose of 30Gy or lower (hazard ratio [HR]2.75, 95% CI 1.66-4.55, p<0.01) and EBRT dose higher than 30Gy (HR 1.43, 95% CI 1.07-1.91, p=0.02) compared with EBRT+BT. No difference was seen using BT alone (HR 1.29, 95% CI 0.92-1.79, p=0.14).

Conclusions: BT utilization for nonsurgically managed endometrial cancer remains low with most patients receiving EBRT alone. Despite concerns of overtreatment in a population with competing causes of death, BT appears to improve survival.