Development and validation of a preoperative prognostic index independent of TNM stage in resected non-small cell lung cancer

BACKGROUND Previously reported prognostic tools for patients with resected non-small cell lung cancer (NSCLC) include factors found postoperatively, but not preoperatively. However, it would be important to predict patient prognosis before NSCLC resection. To suggest a novel preoperative prognostic tool, we evaluated the relationship of preoperative prognostic factors with the survival of patients with resected NSCLC. METHODS We retrospectively reviewed the data of two independent cohorts of patients with completely resected NSCLC. To develop the prognostic index in one cohort, the overall survival (OS) was evaluated using the Cox proportional hazards model. We assessed the disease-free survival (DFS) and OS of three risk groups defined according to the prognostic index. Then, the prognostic index was validated in the other cohort. RESULTS Seven independent risk factors for OS were selected: age ≥ 70 years, ever-smokers, vital capacity <80%, neutrophil-to-lymphocyte ratio ≥ 2.1, cytokeratin 19 fragment >normal limit, non-usual interstitial pneumonia (UIP) pattern, and UIP pattern. Three risk groups were defined: low-risk (36.9%), intermediate-risk (54.0%), and high-risk (9.1%). In the derivation cohort, the 5-year DFS rate was 77.8%, 58.8%, and 22.6% (P < 0.001), and the 5-year OS rate was 95.2%, 70.4%, and 28.9% (P < 0.001), respectively. Multivariate analyses showed that the prognostic index predicted DFS and OS, independent of pathological stage and tumor histology, in both derivation and validation cohorts. CONCLUSIONS We developed and validated a simple preoperative prognostic index composed of seven variables, which may help clinicians predict prognosis before surgery in patients with NSCLC.