Adjuvant radiation therapy improves local control after surgical resection in patients with localized adrenocortical carcinoma.

Purpose: Adrenocortical carcinoma (ACC) is a rare malignancy known for high rates of local recurrence, though the benefit of postoperative radiation therapy (RT) has not been established. In this study of grossly resected ACC, we compare local control of patients treated with surgery followed by adjuvant RT to a matched cohort treated with surgery alone.

Methods And Materials: We retrospectively identified patients with localized disease who underwent R0 or R1 resection followed by adjuvant RT. Only patients treated with RT at our institution were included. Matching to surgical controls was on the basis of stage, surgical margin status, tumor grade, and adjuvant mitotane.

Results: From 1991 to 2011, 360 ACC patients were evaluated for ACC at the University of Michigan (Ann Arbor, MI). Twenty patients with localized disease received postoperative adjuvant RT. These were matched to 20 controls. There were no statistically significant differences between the groups with regard to stage, margins, grade, or mitotane. Median RT dose was 55 Gy (range, 45-60 Gy). Median follow-up was 34 months. Local recurrence occurred in 1 patient treated with RT, compared with 12 patients not treated with RT (P=.0005; hazard ratio [HR] 12.59; 95% confidence interval [CI] 1.62-97.88). However, recurrence-free survival was no different between the groups (P=.17; HR 1.52; 95% CI 0.67-3.45). Overall survival was also not significantly different (P=.13; HR 1.97; 95% CI 0.57-6.77), with 4 deaths in the RT group compared with 9 in the control group.

Conclusions: Postoperative RT significantly improved local control compared with the use of surgery alone in this case-matched cohort analysis of grossly resected ACC patients. Although this retrospective series represents the largest study to date on adjuvant RT for ACC, its findings need to be prospectively confirmed.