Computed Tomography RECIST Assessment of Histopathologic Response and Prediction of Survival in Patients with Resectable Non–Small-Cell Lung Cancer after Neoadjuvant Chemotherapy

This study's objectives were to determine whether tumor response measured by computed tomography (CT) and evaluated using Response Evaluation Criteria in Solid Tumors (RECIST) correlated with overall survival (OS) in patients with non-small-cell lung cancer (NSCLC) after neoadjuvant chemotherapy and surgical resection.We measured primary tumor size on CT before and after neoadjuvant chemotherapy in 160 NSCLC patients who underwent surgical resection. The relationship between CT-measured response (RECIST) and histopathologic response (≤ 10% viable tumor) and OS were assessed by Kaplan-Meier survival, univariable, and multivariable Cox proportional hazards regression.There was a statistically significant association between CT-measured response (RECIST) and OS (p = 0.03). However, histopathologic response was a stronger predictor of OS (p = 0.002), with a more pronounced separation of the survival curves when compared with CT-measured response. In multivariable Cox regression analysis, only pathologic stage and histopathologic response were significant predictors of OS. A 41% overall discordance rate was noted between CT RECIST response and histopathologic response. CT RECIST classified as nonresponders a subset of patients with histopathologic response (8 out of 30 points, 27%) who demonstrated prolonged survival after neoadjuvant chemotherapy.We were unable to show that CT RECIST is a reliable predictor of OS in patients with NSCLC undergoing surgical resection after neoadjuvant chemotherapy. The failure of CT RECIST to predict long-term outcome may be because of the inability of CT imaging to consistently identify patients with histopathologic response. CT RECIST may have only a limited role as an efficacy endpoint after neoadjuvant chemotherapy in patients with resectable NSCLC.