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Differences in survival among patients with specific features of stage T3 lung cancer have been investigated in only a few studies, most of which applied the 7th edition of the tumor, node, and metastasis (TNM) classification or assessed data from small single centers. 

Findings from these previous studies, which show high rates of incomplete pulmonary resection and 5-year survival rates ranging from 20% to 50% post resection, suggest that prognosis may vary between patients who have T3 tumors with chest wall infiltration (CWI) and those who have tumors with other T3 descriptors.¹

To further explore differences within the T3 category, members of the International Association for the Study of Lung Cancer Staging and Prognostic Factors Committee evaluated the completeness of pulmonary resection and long-term survival among patients who had non-small cell lung cancer (NSCLC) with different T3 descriptors based on the 8th (most recent) edition of the TNM staging system. 

In this retrospective analysis, the researchers found that 5-year overall survival varied significantly by tumor size, presence of a separate tumor nodule in the same lobe (SN), parietal pleura infiltration (PL3), and CWI T3 descriptors. Overall survival was significantly worse among patients with T3 tumors characterized by PL3 or CWI than among those with T3 tumors characterized by size or a SN (53% vs 60%, respectively; P=.017).¹

鈥淪ubdividing pathological T3N0M0 tumors according to the presence or absence of CWI or PL3 may increase the prognostic accuracy of tumor staging,鈥� the authors suggested in their report published online ahead of print in the Journal of Thoracic Oncology. They stressed, though, that their analysis was considered exploratory only, since they did not perform the necessary multifaceted analyses for refining the TNM staging system.¹

Extensive database analyzed

The researchers examined the records of the International Association for the Study of Lung Cancer 1999-2010 database, which was used to make refinements for the 8th edition of the TNM classification. The investigators identified patients with pathological T3N0M0 NSCLC tumors (ie, no spread to lymph nodes and no metastatic disease) among those treated with lobectomy or pneumonectomy, with either positive or negative resection margins. Patients who received neoadjuvant or adjuvant treatment were included in the study.

The research team assessed overall survival stratified by T3 descriptors and completeness of resection. 

CWI and PL3 confer lower survival

A total of 1448 patients with T3N0M0 NSCLC, most of whom were from Asia (84.5%), most commonly Japan (83.8%), were included in the study. A majority of tumors were adenocarcinomas (50.9%) or squamous cell carcinomas (38.7%). Incomplete resections of T3 tumors were noted for 7.2% of the study cohort.

Most (82.0%) patients had a single feature constituting a T3 tumor. Incomplete resection rates were highest among T3 tumors with CWI or PL3 (9.8% and 8.4%, respectively) and lowest among tumors classified as T3 by Size 5-7 only (2.9%). Incomplete resection rates were significantly different between a group with CWI or PL3 tumors (8.9%) and a group with Size 5-7 or SN tumors (3.1%, P<.001).

The observed 5-year survival was 55% for the entire cohort. Overall survival varied significantly by individual T3 descriptors (P=0.005). 5-year survival was highest in those with tumors 5-7cm (61%) and lowest for those who had T3 tumors with CWI (50%). 

To address heterogeneity, the researchers consolidated T3 subgroups with similar survival curves. As a result, 2 groups of patients with tumors defined by a single T3 descriptor associated with comparable survival rates were combined (ie, Size 5-7 plus SN and PL3 plus CWI). An additional consolidated group with tumors defined by other or multiple T3 descriptors was analyzed.

The research team found that overall survival was better among patients with T3 tumors categorized by Size 5-7/SN (60%) than among those with T3 tumors characterized by CWI/PL3 (53%, P=.017) and among those with tumors with other/multiple T3 descriptors (47%, P<.001). Similar findings were apparent when only patients with negative resection margins were included in the analysis. Survival outcomes were not significantly different between patients with CWI/PL3 and those with other/multiple T3 descriptors (P=.151).

Refining the T3 category

鈥淭he prognostic ability of the TNM staging system may be improved if T3N0M0 NSCLC was further classified into T3a and T3b subtypes, although the present study findings should only be considered hypothesis-generating,鈥� the study authors wrote. 

Given that survival patterns vary for lung tumors with different T3 descriptors, the prognostic capability of the TNM staging system might be improved, the researchers suggested in their report, by separating lung tumors into a T3aN0M0 subgroup defined by Size 5-7 or a SN and into a T3bN0M0 subgroup defined by CWI, PL3, or multiple features. Redefining stage II on the basis of CWI or PL3, they added, also might increase prognostic accuracy of tumor stage classification.

Published: March 06, 2024