Prognosis factors of Mitotane and loco-regional treatments combination in low-volume metastatic adrenocortical carcinoma

Objective Recommended first line treatment for low burden IV ACC not amenable for radical resection is mitotane in association with multiple local treatments (M + LT). The aim of this study was to evaluate the efficacy, safety and prognostic factors of M + LT to determine patient population that might benefit the most of this strategy. Materials and methods This retrospective monocentric study performed from 2008 to 2020 included stage IVA patients with ≤ 2 tumoral organs who were treated with M + LT. Primary endpoint was time to chemotherapy (TTC) from mitotane initiation and secondary endpoint were overall survival (OS) and controlled disease (CD) rate. Prognosis factors were analyzed using Kaplan-Meier survival analysis and Cox's proportional hazards regression model. Results Thirty-four women and 26 men (60/79, 75.9%) with a median age of 48.1 years old (IQR: 38.3-59.8) were included. One hundred and nine LT were performed with a median of 2 (IQR: 1- 3). CDR was 66.6% (40/60). Median TTC was 42 [95%IC: 15 - 100] months. Oligometastatic and CD patients had significantly longer TTC (HR: 0.35, [95%IC 0.18 - 0.68]; HR: 0.27, [95%IC 0.13 - 0.54]). Oligometastatic and patients with only one metastatic organ had significantly longer OS (HR: 0.37, [95%IC 0.18 - 0.77]; HR: 0.30, [95%IC 0.14 - 0.65]). Conclusion This study supports multiple and combined M + LT to achieve CD. It appears to be particularly efficient in pauci-metastatic ACC as defined by patients with less or equal to 5 metastasis and less than two metastatic organs.