Combination of Mitotane and Locoregional Treatments in Low-volume Metastatic Adrenocortical Carcinoma

Context European and French guidelines for ENSAT stage IV low tumor burden or indolent adrenocortical carcinoma (ACC) recommend a combination of mitotane and locoregional treatments (LRT) as first-line treatment. Nevertheless, the benefit of LRT in combination with mitotane has never been evaluated in this selected group of patients. Objective This work aimed to evaluate the therapeutic strategy of LRT combined with mitotane in patients with low tumor burden stage IVA ACC. Methods A retrospective chart review was performed from 2003 to 2018 of patients with stage IV ACC with 2 or fewer tumoral organs who received mitotane in our center. The primary end point was the delay between mitotane initiation and first systemic chemotherapy. Secondary end points were progression-free survival (PFS) and overall survival (OS) from mitotane initiation. Adjusted analyses were performed on the main prognostic factors. Results Out of 79 included patients, 48 (61%) patients were female and the median age at stage IVA diagnosis was 49.8 years (interquartile range [IQR], 38.8-60.0 years). Metastatic sites were mainly lungs (76%) and liver (48%). Fifty-eight (73%) patients received LRT including adrenal bed radiotherapy (14 patients, 18%), surgery (37 patients, 47%), and/or interventional radiology (35 patients, 44%). Median time between mitotane initiation and first chemotherapy administration was 9 months (IQR, 4-18 months). Median PFS1 (first tumor-progression) was 6.0 months (95% CI, 4.5-8.6). Median OS was 46 months (95% CI, 41-68). PFS1, PFS2, and OS were statistically longer in the mitotane plus LRT group compared to the mitotane-only group (hazard ratio [HR] = 0.39; 95% CI, 0.22-0.68; HR = 0.35; 95% CI, 0.20-0.63; and HR = 0.27; 95% CI, 0.14-0.50, respectively). Ten (13%) patients achieved complete response (CR), all from the mitotane plus LRT group. Conclusion Our results endorse European and French guidelines for stage IV ACC with 2 or fewer tumor organs and favor the combination of mitotane and LRT as first-line treatment. For the first time, a significant number of CRs were observed. Prospective studies are expected to confirm these findings.