Adrenocortical carcinoma (ACC) is a rare malignancy with high rates of recurrence and poor prognosis. The role of radiotherapy (RT) in localized ACC has been controversial, and RT is not routinely offered.

To evaluate the benefit of adjuvant RT on outcomes in ACC.

This is a retrospective propensity-matched analysis.

All patients were seen through the University of Michigan's Endocrine Oncology program, and all those who underwent RT were treated at the University of Michigan.

Of 424 patients with ACC, 78 were selected; 39 patients underwent adjuvant radiation.

Adjuvant RT to the tumor bed and adjacent lymph nodes.

Time to local failure, distant failure, or death.

Median follow-up time was 4.21 years (95% CI, 2.79 to 4.94). The median radiation dose was 55 Gy (range, 45 to 60). The 3-year overall survival estimate for patients improved from 48.6% for patients without RT (95% CI, 29.7 to 65.2) to 77.7% (95% CI, 56.3 to 89.5) with RT, with a hazard ratio (HR) of 3.59 (95% CI, 1.60 to 8.09; P = 0.002). RT improved local recurrence-free survival (RFS) from 34.2% (95% CI, 18.8 to 50.3) to 59.5% (95% CI, 39.0 to 75.0), with an HR of 2.67 (95% CI, 1.38 to 5.19; P = 0.0035). RT improved all RFS from 18.3% (95% CI, 6.7 to 34.3) to 46.7% (95% CI, 26.9 to 64.3), with an HR 2.59 (95% CI, 1.40 to 4.79; P = 0.0024).

In the largest single institution study to date, adjuvant RT after gross resection of ACC improved local RFS, all RFS, and overall survival in this propensity-matched analysis. Adjuvant RT should be considered a part of multidisciplinary management for patients with ACC.