Overuse of external beam radiotherapy for stage I endometrial cancer

Radiation therapy has long been part of the treatment of endometrial cancer. Despite the long history of radiation use, prospective trials in the United States and Europe have been unable to demonstrate a survival benefit with adjuvant radiotherapy compared with observation. Whereas radiation has been associated with a decreased rate of locoregional failure, the treatment is also associated with substantial toxicity. However, a randomized trial published in 2010 demonstrated that, compared with external beam radiation therapy (EBRT), vaginal brachytherapy was less toxic and as effective in reducing locoregional relapses.

We examined patterns of use of external beam radiation therapy for women with high intermediate risk endometrial cancer.

We examined the use of external beam radiation therapy in women registered in the National Cancer Data Base with high intermediate risk, stage I endometrial cancer treated from 2008 through 2012. High intermediate risk was defined as age > 60 years with a stage IA, grade 3 tumors or stage IB, grade 1 or 2 tumors. Multivariable models of EBRT use were developed.

Among 8242 women, 915 (11.1%) received EBRT, 2614 (31.7%) were treated with brachytherapy, and 4713 (57.2%) did not receive any adjuvant radiation. The use of EBRT was 18.1% in 2008 and declined to 8.6% in 2012, whereas the use of brachytherapy rose each year from 26.5% in 2008 to 37.6% in 2012 (P < .0001). External beam radiation was administered to 7.9% of patients with stage IA/grade 3 tumors, 8.8% of those with stage IB/grade 1 cancers, and to 15.2% of women with stage IB/grade 2 neoplasms (P < .0001). EBRT was utilized in 10.1% of women who underwent lymphadenectomy compared with 22.0% who did not undergo lymphadenectomy (P < .0001). In a multivariable model, black women were more likely to receive EBRT than white women (relative risk [RR], 1.33; 95% confidence interval [CI], 1.03-1.70). Similarly, patients in the eastern United States, those treated at community cancer centers and comprehensive community cancer programs, patients in metropolitan areas, and those diagnosed in earlier years were more likely to undergo EBRT. Patients with stage IB/grade 2 tumors (RR, 1.96; 95% CI, 1.65-2.32) were more likely to receive EBRT than those with stage IA/grade 3 neoplasms. Those women who did not undergo lymphadenectomy were more than twice as likely to receive EBRT compared with those who had a lymphadenectomy (RR, 2.32; 95% CI, 1.99-2.72).

Despite data from randomized trials, approximately 9% of women with high intermediate risk of endometrial cancer continue to receive EBRT. Performance of lymphadenectomy is associated with a lower likelihood of external beam radiation therapy.