Adjuvant radiation therapy improves outcome of patients with surgical resected adrenocortical carcinoma

Purpose: Adrenocortical carcinoma (ACC) is a rare malignancy known for high rates of recurrence and poor prognosis. Previous studies revealed controversial roles of adjuvant radiation therapy (RT) in patient management. This study aimed to investigate the role of adjuvant RT in postoperative ACC patients.

Methods: Patients with histologically confirmed ACC who underwent surgical resection in the Surveillance, Epidemiology, and End Results (SEER) database between 2004 and 2020 were enrolled. Propensity score matching (PSM) was used to balance baseline characteristics between patients receiving adjuvant RT and patients who did not receive RT. Overall survival (OS) and recurrence-free survival (RFS) was analyzed using the Kaplan-Meir method. Risk factors associated with survival outcome was analyzed by univariate and multivariate Cox regression analyses. Subgroup analyses were stratified by European Network for the Study of Adrenal Tumors (ENSAT) disease stage or chemotherapy. A joint retrospective analysis of stage III patients was performed based on data obtained from Ruijin Hospital and MD Anderson Cancer Center.

Results: Among the 700 patients enrolled, 137 patients undergoing postoperative RT were matched with 137 patients who did not receive RT. Overall survival for patients with adjuvant RT was better than patients without RT (log-rank P = 0.015). The 3-year and 5-year OS were 55.2 and 47.1% for patients with RT, vs 42.6 and 34.0% for patients without RT. Multivariate analysis showed adjuvant RT was independently associated with lower mortality (hazard ratio [HR] 0.63, P = 0.007). Subgroup analysis stratified by disease stage demonstrated that adjuvant RT showed the most favorable effect in stage III patients (HR 0.53, P = 0.013). Furthermore, joint analysis of two centers showed a tendency of better OS and local control rate for stage III patients with mitotane plus RT than those with mitotane alone.

Conclusion: Our study indicated that adjuvant RT was associated with improved prognosis for ACC patients, especially for patients with ENSAT stage III diseases. Integrating adjuvant RT into standard care of ACC may be considered.