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

ABSTRACT

PURPOSE: 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 AND MATERIALS 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). CONCLUSION: 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.