Relationship between tumor size and survival in non-small cell lung cancer (NSCLC): An analysis of the Surveillance, Epidemiology, and End Results (SEER) registry.

Abstract

7047 Background: Tumor size is a known prognostic factor for early stage (I and II) NSCLC, but its significance in node positive or locally advanced NSCLC has not been determined. We sought to evaluate its prognostic value in early and locally advanced NSCLC and create a nomogram incorporating tumor size and other prognostic variables to predict survival. Methods: The SEER registry was queried for patients (pts) with NSCLC, aged 20-103 and diagnosed between 1998 and 2003. Pts with extra-pulmonary metastases or distant lymph node metastases were excluded. Tumor size was analyzed as a continuous variable. Other demographic variables included age, gender, race, histology, primary tumor extension, node status and primary treatment modality (surgery vs radiation). Log-rank test was performed to evaluate the relationship between these variables and overall survival (OS). Cox proportional hazard model was used to evaluate whether tumor size was an independent prognostic factor. Results: 52,287 eligible pts were divided into 16 subgroups based on primary tumor extension and node status. For example, in group 1, tumor was confined to one lung with no nodes involved; pts in group 12 had tumor invading the mediastinum (T4 by extent) and positive ipsilateral mediastinal nodes. Tumor size had a significant effect on OS in almost all groups after adjustment for age, sex, race, histology, node status, primary tumor extension and primary treatment modality. Our model incorporating tumor size had significantly better predictive accuracy (larger C index) than our alternative model not including this information (p<0.0001). We then developed a nomogram incorporating tumor size, age, gender, race, histology, nodule stage, and tumor extension with the intent to predict OS. In subsequent bootstrap verification, the predicted 2-year OS from the nomogram was almost identical to the actual observed 2-year OS with a very slim biases of estimates. Conclusions: Tumor size is an independent prognostic factor, including pts with node positive or locally advanced NSCLC. We successfully created a nomogram incorporating tumor size and other clinical variables to predict survival.