Visceral pleura invasion impact on non-small cell lung cancer patient survival: its implications for the forthcoming TNM staging based on a large-scale nation-wide database.

Introduction: No analyses have been reported on the impact of visceral pleura invasion (VPI) on staging, in relation with the International Association for the Study of Lung Cancer proposals for the 7th edition of the tumor, node, metastasis (TNM) classification of the International Union Against Cancer staging system. The purpose of this study was to evaluate the impact of VPI on survival and propose a method of incorporating VPI status into the TNM classification.

Methods: We reviewed the data on 9758 non-small cell lung cancer patients, who underwent anatomic surgical resection in 1999, accumulated by the Japanese Joint Committee for Lung Cancer Registration, to gain insight into their clinicopathologic characteristics and outcomes. VPI was defined as tumor extension beyond the elastic layer of the visceral pleura. Patients were divided into nine groups according to VPI status and tumor diameter, in accordance with the International Association for the Study of Lung Cancer proposals.

Results: On the basis of survival, the nine groups were divided into the following five levels: tumors < or =2 cm without VPI; tumors < or =2 cm with VPI and tumors 2.1 to 3 cm without VPI; tumors 2.1 to 3 cm with VPI and tumors 3.1 to 5 cm without VPI; tumors 3.1 to 5 cm with VPI and tumors 5.1 to 7 cm without VPI; and tumors 5.1 to 7 cm with VPI and tumors >7 cm without VPI or T3 tumors.

Conclusions: The T status of tumors, 7 cm or less, with VPI should be upgraded to the next T level in the future edition of the TNM classification of International Union Against Cancer staging system.