Loco-Regional Therapies in Oligometastatic Adrenocortical Carcinoma

SIMPLE SUMMARY: The treatment recommended for stage IVa Adrenocortical carcinoma (ACC) not amenable to radical resection is the mitotane plus loco-regional treatment (LR) strategy, which has not yet been validated. Moreover, prognosis factors for this strategy are not yet established. This study aimed to determine which stage IVa ACC patient population would benefit the most from this association. For this purpose, we reviewed all stage IVa patients (≤2 tumoral organs) treated with mitotane and LR from 2008 to 2021 in our institution. This study included 60 patients and 109 LR were performed. The primary endpoint was disease control (DC). We found that DC was associated with longer Time to second line Treatments (TTC). Moreover, DC rate was higher in patients that had ≤5 metastases or a maximum metastasis diameter below 3 cm. Based on those results we propose the first definition of oligometastatic ACC: stage IVa patients with ≤5 metastases or a maximum metastasis diameter below 3 cm. It is vitally important that scientists are able to describe their work simply and concisely to the public, especially in an open-access on-line journal. ABSTRACT: Objective: The recommended first-line treatment for low-tumor-burden ACC (stage IVa ACC) not amenable to radical resection is mitotane in association with loco-regional treatments (LRs). The aim of this study was to determine the patient population that would benefit the most from LR. Materials and methods: This retrospective monocentric expert center chart review study was performed from 2008 to 2021 and included stage IVa patients (≤2 tumoral organs) treated with LR (either radiotherapy, surgery, or interventional radiology). The primary endpoint was disease control (DC). Correlations between DC, time to systemic chemotherapy (TTC), overall survival (OS), and tumor characteristics were analyzed using Kaplan–Meier survival analysis and Cox’s proportional hazards regression model for multivariate analysis. Results: Thirty-four women (57%) and 26 men with a median age of 48.1 years (IQR: 38.3–59.8) were included. One hundred and nine LRs were performed, with a median of 2 (IQR: 1–3) per patient. DC was achieved in 40 out of 60 patients (66.7%). Patients with DC had a significantly longer TTC (HR: 0.27, p < 0.001) and OS (HR: 0.22, p < 0.001). Patients with less than or equal to 5 metastases (HR: 6.15 (95% CI: 1.88–20.0), p = 0.002) or a maximum metastasis diameter below 3 cm had higher rates of DC (HR: 3.78 (95% CI: 1.09–13.14), p = 0.035). Conclusion: stage IVa ACC patients with ≤5 metastases or a maximum metastasis diameter below 3 cm had favorable responses to LR. We propose the name oligometastatic ACC for this subgroup of patients.