Purpose: To assess the impact of cell type, age, and gender in addition to pathologic tumor, node, metastasis (TNM) stage in surgically managed stage I-IIIA non-small cell lung cancer (NSCLC) cases from the international staging database of the International Association for the Study of Lung Cancer.
Material and methods: From the 67,725 cases of NSCLC submitted to the staging database, 9137 surgically managed cases were selected for which all the following variables were available: pathologic stage, age, gender, and specific histologic cell type. Performance status and smoking history were examined in subsets. Methods used were Cox proportional hazards regression and recursive partitioning and amalgamation (RPA) analyses.
Results: Pathologic TNM stage, age, and gender were all independently prognostic for survival. The bronchioloalveolar carcinoma (BAC) subtype had superior survival over other cell types despite the potential for heterogeneity in this group. Adjusted comparisons revealed a small survival advantage for squamous cell carcinomas over non-BAC adenocarcinoma histology and also over large cell, though the effect appeared to be limited to the male patients. RPA revealed the importance of TNM stage primarily, and age was prognostic within stage groups. Cell type was not found to add prognostic value in the RPA analysis. Prognostic groups were formed based on the RPA output, and the prognostic value of these groupings was validated using the North American Surveillance, Epidemiology, and End Results Registries. Performance status and smoking history were prognostic in the subsets where data were available. Effects of other variable were not influenced by the inclusion of smoking status in regression models.
Conclusions: Age and gender are confirmed as important prognostic factors in surgically resected NSCLC. Cell type is less important, although the small population of cases classified as BAC have a survival advantage over other histologies, and there may be a small survival advantage for squamous cell carcinomas over non-BAC adenocarcinomas. Imbalances between stage, gender, and cell type at presentation may lead to a misleading result with respect to cell type in unadjusted analyses. Pathologic TNM category is the most important prognostic factor in this analysis.