Is response evaluation criteria in solid tumors (RECIST) effective in patient selection for radical resection after neoadjuvant immunotherapy with advanced NSCLC?

BACKGROUND: Neoadjuvant immunotherapy combined with chemotherapy has been used to treat locally advanced non–small cell lung cancer (NSCLC). Several systems have been developed for response evaluation. The aim of this study was to evaluate the predictive value of response evaluation criteria in solid tumors (RECIST) and propose modified RECIST (mRECIST). METHODS: Eligible patients received chemotherapy combined with personalized neoadjuvant immunotherapy. Radical resection was subsequently performed for potentially resectable tumors evaluated by RECIST. The resected specimens were evaluated to determine the response to neoadjuvant therapy. RESULTS: A total of 59 patients received radical resection following neoadjuvant immunotherapy combined with chemotherapy. According to RECIST, four patients had complete remission, 41 had partial remission, and 14 had progressive disease. Postoperative pathological examination showed 31 patients achieved complete pathological remission, and 13 achieved major pathological remission. The final pathological results were uncorrelated with RECIST assessment (p = 0.086). The ycN stage and pN stage were irrelevant (p < 0.001). When the cutoff of sum of diameters (SoD) is 17%, the Youden's index reached its highest value. A correlation was found between mRECIST and final pathological results. Patients with squamous cell lung cancer showed higher proportions in objective response (OR) (p < 0.001) and complete pathological remission (CPR) (p = 0.001). A shorter time to surgery (TTS) was correlated with a better OR (p = 0.014) and CPR (p = 0.010). The decrease in SoD was correlated with better OR (p = 0.008) and CPR (p = 0.002). CONCLUSIONS: mRECIST was effective for patient selection for radical resection after neoadjuvant immunotherapy with advanced NSCLC. Two modifications were suggested for RECIST: (1) the cutoff value was adjusted to 17% for partial remission. (2) Changes in lymph nodes on computed tomography were eliminated. A shorter TTS, a larger decrease in SoD and squamous cell lung cancer (vs. adenocarcinoma) were correlated with better pathological responses.