T1/T2 non-small-cell lung cancer treated by lobectomy: Does tumor anatomic location matter?

Background: The effect of tumor location on long-term survival after lobectomy for stage I non-small-cell lung cancer is unclear. Current data are limited to a retrospective single-institution series. We sought to determine if tumor anatomic location (i.e., the particular lobe that was involved) confers a survival advantage based on population-based data. Methods: Using the Surveillance, Epidemiology and End Results database (1988-2007), we identified patients who underwent lobectomy for pathologic T1/T2 adenocarcinoma or squamous cell carcinomas. Wedge resections, segmentectomies, and pneumonectomies were excluded. We evaluated the association between the particular lobe that was involved, lymph node (LN) yield, and survival using the Kaplan-Meier method. To adjust for potential confounders, we used a Cox proportional hazards regression model. Results: We identified 13,650 patients who met our inclusion criteria. There were significant differences in unadjusted overall (P = 0.03) and cancer-specific survivals (P = 0.03) based on tumor location. However, after adjusting for patient factors, geographic location of treatment, and tumor characteristics, we found that tumor location was not associated with significant differences in survival. We found that male gender, black race, squamous cell histology, increasing grade, and age were independent negative predictors of survival. Higher LN yields were independently associated with improved survival. Although adjusted survival rates were not significantly different, there were significant differences (P < 0.0001) in LN yield based on tumor location; right middle lobe had the lowest yield (5.1 nodes), and left upper lobe had the highest yield (eight nodes). Conclusions: LN counts are independent predictors of survival. Although it is associated with significant difference in LN yield, tumor location is not an independent predictor of survival. Age, race, gender, tumor size, histology, and grade appear to be more important prognostic factors. These data suggest that treatment of T1/T2 non-small-cell lung cancer should be dictated by the same oncologic principles, regardless of tumor location.