Prognostic Significance of Tumor Size in Patients with Stage III Non–Small-Cell Lung Cancer: A Surveillance, Epidemiology, and End Results (SEER) Survey from 1998 to 2003

Increased tumor size is a known risk for poor outcomes in patients with stage I and II non–small cell lung cancer (NSCLC), who are treated with surgery or radiotherapy. However, there is limited information regarding the impact of tumor size on the outcomes of patients with mediastinal lymph node involvement. We conducted a Surveillance, Epidemiology, and End Results (SEER) database analysis to evaluate the prognostic significance of tumor size in patients with unresected stage III NSCLC. The SEER registry was queried for patients with unresected NSCLC stage III and no malignant pleural effusion, aged 21 years or older, and diagnosed between 1998 and 2003. Tumor size was defined as S1 (0.1–3cm), S2 (3.1–5cm), S3 (5.1–7cm), and S4 (7.1–20cm). Demographic variables included age, sex, race and histology. Overall survival (OS) and disease-specific survival (DSS) were estimated by the Kaplan–Meier method, and the Cox proportional hazard model was used to evaluate whether tumor size remained an independent risk factor in multivariable analysis. A total of 12,315 patients met the eligibility criteria. Median age at diagnosis was 70 years and most patients were men (58.7%) and white (81.3%). Tumor size was an independent predictor for both OS (p < 0.0001) and DSS (p < 0.001) in all subgroups of patients. Tumor size is an independent predictor for OS and DSS in patients with unresected stage III NSCLC, and should be considered in the stratification of patients treated in this setting after validation of this finding in additional studies.