Clinical Verification of a Nomogram Model for Prediction of Brain Metastases in Patients with pⅢA-N2 Non-Small Cell Lung Cancer

Abstract

Brain metastasis is one of the most common failure patterns of pⅢA-N2 non-small cell lung cancer (NSCLC) after complete resection. Prophylactic Cranial Irradiation (PCI) can improve intracranial control but not overall survival. Thus, it is particularly important to identify risk factors that are associated with brain metastasis and subsequently provide instructions for selecting patients who will optimally benefit from PCI. We have reported a nomogram model which was established based on the condition of histology, bronchial invasion, perineural invasion, and adjuvant chemotherapy, through which we can predict high risk brain metastases in patients with pⅢA-N2 NSCLC. The purpose of this study is to verify the accuracy of the nomogram model by using new cases information. Between January 1, 2015 and December 31, 2019, patients of pⅢA-N2 NSCLC were retrospectively analyzed, to verify the consistency between actual and predictive brain metastases. The verification group was divided into two groups according to the years when genetic testing has been widely used in clinic (group1:2015-2016, group2:2017-2019). ROC curves and calibration curves were chosen for validation. A total of 770 patients were enrolled in our retrospective study (group1:294 patients, group2: 476patients). The 1-, 3- and 5-year survival rates were 97.2%, 76.5%, 63.2% in group1, and 95.8%, 84.5%, 76.9% in group2, respectively. The 1-, 3- and 5-year brain metastasis rates were 7.9%, 19.7%, 25.8%, and 5.4%, 14.5%, 26.3% in group2, respectively. The AUC were 0.74 (95% CI:0.72 - 0.76) in group1, and 0.71(95% CI:0.70 - 0.73) in group 2.The 1.3.5-year calibration curves of the two groups show that the prediction is in good agreement with the actual observation. The nomogram model can predict brain metastases high risk patients with pⅢA-N2 NSCLC. Whether gene test or not, it can be used as a basis to screening out patients of high-risk brain metastases in future clinical trials for PCI.