PURPOSE:To improve the predictive value of lung cancer staging, we investigated the effect of tumor size on prognosis of Stage IA Non-Small Cell Lung Cancer (NSCLC) patients.
METHODS:Stage I lung cancer (T1–2N0M0) patients who had undergone surgical resection from January 1, 1991 through December 31, 2004 were identified by the cancer registry of Beth Israel Deaconess Medical Center in Boston, Massachusetts. 405 patients were grouped into various categories according to tumor size. Overall (OS), as well as disease free survival (DFS) periods were compared for statistical significance.
RESULTS:When patients who fit the current T1 descriptor (≤;3cm) were subdivided into those with tumors ≤;2cm (n=193) and those with tumor size >2cm but ≤;3cm (n=99), significant differences were observed in both OS (p=.018) and DFS (p=.021). Similarly, statistically significant differences were observed in patients whose tumor sizes were ≤;2cm (n=193) and >2cm (n=212) (OS, p=.011, DFS, p=.001). As expected, a statistically significant difference was observed in DFS (p=.002) for patients with tumor size greater or less than 3cm (current cut off point between T1 and T2) but there was no significant difference in the OS between those patients (p=.241).
CONCLUSION:A distinct subgroup within T1, comprising of 49% of the resected stage I NSCLC patients, was identified. Our study strongly suggests that the T1 descriptor should be subdivided into (T1a < 2cm) and (2 < T1b < 3cm) categories to reflect the observed prognostic differences. This recommendation agrees with the revisions proposed by the International Association for the Study of Lung Cancer for the next (7th) edition of the staging system for lung cancer.
CLINICAL IMPLICATIONS:Based on earlier detection and safer surgery, patients with tumors smaller than 2 cm have significantly better survival than those with larger node-negative tumors. Subdivision of the T1 descriptor at 2 cm reflects this clinically relevant difference in survival. This is important as more patients are being diagnosed with smaller tumors and decisions about adjuvant therapy require identification and stratification of clear prognostic groups.
DISCLOSURE:Chao Ye, No Financial Disclosure Information; No Product/Research Disclosure Information