Adjuvant radiation improves survival outcomes in adrenocortical carcinoma: A population-based study

The aim of this study was to evaluate the clinical benefits and outcomes of adjuvant radiation therapy on adrenocortical carcinoma (ACC) patients. All patients with ACC that were reported between 2010 and 2015 were identified from the Surveillance, Epidemiology, and End Results database. A forward-stepwise Cox proportional hazards regression was used to identify independent risk factors. A new nomogram was created to predict overall and cancer-free survival probabilities at 1, 3, and 5 years for ACC patients. The concordance index, the area under the receiver operating characteristic curve, calibration curves, and decision curve analysis were used to validate the accuracy and reliability of the model. A total of 426 ACC patients were enrolled in this study, of which 84 (19.7%) cases underwent adjuvant radiation therapy (RT). Six factors (age, T stage, type of surgery, radiation, and bone and liver metastases) were significantly related to overall survival (OS) (P < .05). Five factors (T stage, type of surgery, radiation, and bone and liver metastases) were significantly related to cancer-specific survival (CSS) (P < .05). A nomogram for OS and CSS was constructed. The area under the receiver operating characteristic curve values for 1-, 3-, and 5-year OS were 0.85, 0.818, and 0.814, respectively, and for CSS, they were 0.839, 0.803, and 0.796, respectively. C-indices were 0.756 and 0.749 for OS and CSS, respectively, indicating that the nomograms for OS and CSS had satisfactory discriminative power. A good consistency between the observed and the predicted survival was found in the calibration curves, and the nomogram has a good net clinical benefit, which is presented in the decision curve analysis curves. Our study demonstrates that adjuvant RT can produce a significant improvement in survival outcomes for ACC patients and suggests that adjuvant RT should routinely be applied in ACC patients.