Clinical N Staging Subclassification for Stage III-N2 NSCLC Patients Undergoing Trimodality Therapy: A Good Beginning Is Half the Battle.

Abstract

Lung cancer patients with stage III-N2 disease may benefit from the subclassification of nodal involvement before decision-making. We aimed to evaluate whether the clinical N descriptor subclassification predicts prognosis in patients undergoing trimodality therapy for stage III-N2 non-small cell lung cancer. Using our institutional registry between 2003 and 2019, we analyzed 899 consecutive patients with stage III-N2 non-small cell lung cancer undergoing neoadjuvant concurrent chemoradiotherapy followed by surgery. We subclassified clinical N2 into cN2a and cN2b on the basis of imaging and histopathologic results. Recurrence-free survival and overall survival were compared by N2 subclassification and separately by histologic type, using competing risks models and Cox proportional hazards models. By the proposed N subclassification, 503 (56.0%) and 396 (44.0%) patients were assigned to cN2a and cN2b, respectively. During a median follow-up of 53.1 months, 492 patients had recurrence and 477 died. The hazard ratios for recurrence comparing cN2b with cN2a after adjustment for age, sex, comorbidities, clinical T category, and histologic type were 1.22 (95% CI, 1.03-1.46). The adjusted hazard ratios for mortality comparing cN2b to cN2a were 1.43 (1.19-1.71). When stratified by histologic type, cN2b had a higher risk of mortality compared with cN2a in both adenocarcinoma and squamous cell carcinoma. In our study evaluating the International Association for the Study of Lung Cancer's approach to subclassify the clinical N descriptor for stage III-N2 non-small cell lung cancer patients, cN2b had a higher risk of recurrence and mortality compared with cN2a, suggesting that clinical N subclassification may be a valuable predictor for stage III-N2 patients.