A Retrospective Cohort Analysis of the Efficacy of Adjuvant Radiotherapy after Primary Surgical Resection in Patients with Adrenocortical Carcinoma

Abstract

Adrenocortical carcinoma (ACC) is a rare malignancy with high recurrence and mortality rates. The role of adjuvant radiation therapy (RT) to improve outcome remains unclear. The aim of this study was to evaluate the impact of adjuvant RT on overall survival and recurrence rates of ACC patients. We conducted a retrospective cohort study of select ACC patients who were seen at The University of Texas MD Anderson Cancer Center (MDACC) between 1998 and 2011. All patients in this study underwent primary tumor resection and received adjuvant RT within 3 months of primary surgical resection prior to referral to the MDACC. We compared patients who had surgery and adjuvant RT with patients who had surgery alone. Baseline characteristics and adjuvant mitotane use were not significantly different between the adjuvant RT group (n = 16) and the non-RT group (n = 32). Local recurrence occurred in seven patients (43.8%) who received RT and 10 patients (31.3%) in the control group. At 5 yr, the estimated local recurrence-free rate (95% confidence interval) was 53% (32-87%) in the RT group and 67% (52-86%) in the non-RT group (P = 0.53). The distributions of time to distant recurrence and recurrence-free survival were not significantly different between the two groups. Using a multivariate Cox proportional hazards model for overall survival, the hazard ratio for RT use was 1.593 (95% confidence interval, 0.707-3.589; P = 0.26) after adjusting for stage and adjuvant mitotane therapy. ACC has high rates of recurrence. In our study, RT did not improve clinical outcomes in patients who received their initial care in the community. We believe there is a need for a collaborative, multicenter, prospective randomized trial to evaluate the role of adjuvant treatments (both mitotane and RT) to assess their impact on recurrence patterns and survival.