A2-01: Prognostic significance of AJCC T2 descriptor-visceral pleura invasion, hilar atelectasis or obstructive pneumonitis for stage IB non-small-cell lung cancer (NSCLC) is dependent on tumor size

Abstract

The T2 descriptor in the AJCC staging for non-small-cell lung cancer (NSCLC) contains several non-size based criteria in addition to the criterion of tumor size greater than 3 cm. It remains unknown if there are survival differences between patients whose tumors were staged according to these non-size based criteria when compared to patients whose tumors were staged according to tumor size. We analyzed 10,545 stage IB NSCLC patients from the California Cancer Registry (CCR) from 1989 to 2003. These patients were staged as IB disease according to three non-overlapping main criteria: 1) tumor size [T2S]; 2) visceral pleura invasion, hilar atelectasis or obstructive pneumonitis [T2P]; 3) main bronchus involvement ≈ 2 cm from the carina [T2C]. Univariate survival analyses were conducted using the Kaplan-Meier method. Multivariate survival analyses were performed using Cox proportional hazards ratios. 5385 (51.1%) IB patients were staged according to tumor size [T2S], 4557 (43.2%) patients were staged by visceral pleura invasion, hilar atelectasis or obstructive pneumonitis [T2P] and 603 (5.7%) patients were staged by main bronchus involvement ≈ 2 cm from the carina [T2C]. 35.7% of the IB patients due to visceral pleura invasion, hilar atelectasis or obstructive pneumonitis [T2P] and 29.7% of the patients due to main bronchus involvement ≈ 2 cm from the carina [T2C] had tumors 3 cm or smaller. There was statistical significant difference in the 5-year survivorship and median overall survival (OS) among the 3 types of stage IB NSCLC patients: (T2C: 38.6% and 39 months; T2P: 38.0% and 38 months; T2C: 40.3% and 39 months; P = 0.0031). The 5-year survival and median OS of these IB patients with tumor 3 cm or smaller were 53.3% and 67 months for T2P and 52.6% and 73 months for T2C respectively, similar to the 53.2% 5-year survival and 67 months of median OS for stage IA patients. Cox proportional hazards model revealed that T2P > 3 cm is a poor prognostic factor (vs. T2S, Hazard Ratio [HR] = 1.13, 95% Confidence Interval (CI) = 1.06-1.20) while T2P ≈ 3 cm was a favorable prognostic factor (vs. T2S, HR = 0.87, 95% CI = 0.80-0.95). T2C > 3 cm (vs. T2S, HR = 0.98, 95% CI = 0.84-1.13) and T2C ≈ 3 cm (vs. T2S, HR = 0.86, 95% CI = 0.69-1.08) were not independent poor prognostic factors. Non-size based T2 descriptors-visceral pleura invasion, hilar atelectasis or obstructive pneumonitis are poor independent prognostic factors when the tumor size was greater than 3 cm. Stage IB NSCLC patients staged by non-size based criteria T2 descriptors whose tumors were 3 cm or smaller had survival similar to stage IA NSCLC patients. Future proposed changes to the AJCC T2 descriptor, the non-size based criteria should be linked to size criteria rather than as independent criteria. The prognostic significance of the T2C criterion requries further studies.