Adjuvant Radiation is Associated with Improved Survival for Select Patients with Non-metastatic Adrenocortical Carcinoma

Adrenocortical carcinoma (ACC) is a rare and aggressive malignancy for which surgery is the mainstay of treatment and for which adjuvant radiation is infrequently employed; however, small, single-institution series suggest adjuvant radiation may improve outcomes. All patients with non-metastatic ACC treated with either surgery alone or surgery followed by adjuvant radiation were identified in the 2004-2013 National Cancer Database. Factors associated with receipt of radiation and the impact of adjuvant radiation on survival were determined by multivariable analysis. Of 1184 patients, 171 (14.4%) received adjuvant radiation. Patient demographics were similar between the two groups, but those receiving radiation were more likely to have had positive margins following surgery (37.4 vs. 14.6%; p < 0.001), evidence of vascular invasion (14.0 vs. 5.1%; p = 0.05), and receive concurrent chemotherapy (57.3 vs. 28.8%; p < 0.001). After adjustment for tumor and other treatment factors, only positive margins following surgery was associated with an increased likelihood of receiving adjuvant radiation (odds ratio 3.84, 95% confidence interval [CI] 1.95-7.56). Radiation therapy did not confer a difference in median overall survival in the general cohort. However, for patients with positive margins, adjuvant radiation was associated with a 40% decreased yearly risk of death after adjustment for concurrent chemotherapy (hazard ratio 0.60, 95% CI 0.40-0.92; p = 0.02). This survival advantage was not evident for other traditional high-risk features. Adjuvant radiation appears to decrease the risk of death in ACC patients with positive margins following surgical resection, but only a small percentage are currently receiving radiation. Multidisciplinary treatment with surgery and radiation should be considered for these patients.