Adjuvant radiotherapy after surgical resection for adrenocortical carcinoma: A systematic review of observational studies and meta-analysis.

Historically, the role of adjuvant radiotherapy (RT) for patients with adrenocortical carcinoma (ACC) has been controversial. The objective of this research is to review systematically the literature evaluating the role of adjuvant RT in patients with ACC undergone a surgical resection.The electronic databases were searched for articles published until July 2017 without language restriction: Lilacs, Medline, Embase, and the Cochrane. Two reviewers independently appraised the eligibility criteria and extracted data. When possible, a fixed-effect meta-analysis was done. The systematic review (SR) followed all the criteria of the MOOSE guideline.Overall, 382 citations were identified. After the screening of titles and abstracts, 12 articles (eight case series [48 patients] and 4 cohort studies [136 patients]) were included in the final analysis. For the local recurrence, the pooled relative risk (RR) was RR = 0.46 (95% confidence interval: 0.28-0.75), in favor of adjuvant RT when compared with surgery alone. Concerning overall mortality and disease recurrence, no significant difference between adjuvant RT and surgery was detected, RR = 0.77 (CI 95% 0.49-1.22, P = 0.27), and RR = 0.95 (IC 95% 0.74-1.24, P = 0.67). In all cohort studies, the acute toxicities were graduated as mild and self-limited with nausea and fatigue being the most common symptoms. Only one case (1/50) of impairment of kidney function was detected as late toxicity in these studies.This SR and meta-analysis indicate that adjuvant RT dramatically reduces the local recurrence of ACC after surgery. Moreover, the treatment has a low acute and late toxicity, resulting in a high therapeutic index. Further, prospective studies are needed to confirm or refute the role of RT on survival and disease recurrence.