Tumor Invasion of Extralobar Soft Tissue Beyond the Hilar Region Does Not Affect the Prognosis of Surgically Resected Lung Cancer Patients

Abstract

Visceral pleural invasion, which is defined as tumor extension beyond the elastic lamina, is one of the most important prognostic factors in patients who have undergone curative resection for non-small cell lung cancer. However, in pathologic slides, pleural elastic lamina could not be found in the hilar region in which the pleura is reflected. Till date, when cancer cells are seen in this region, a basical agreement dealing with T factor is controversial among pathologists. The purpose of this study is to evaluate the significance of tumor invasion of that region as a prognostic factor. We reviewed 91 cases of surgically resected lung cancer in which invasion of the hilar region was visible macroscopically. By microscopic examination, we divided them into three groups: a group in which no cancer cells are seen in the soft tissue beyond the hilar region (group A), a group in which cancer cells are seen in the soft tissue beyond the hilar region (group B), and a group in which cancer cells could not be seen in the soft tissue beyond the hilar region but invade into the mediastinal visceral pleura at some other site (group C). We then evaluated the clinicopathologic characteristics of the patients and their outcome. There was no statistically significant difference in the 5-year overall survival rate or disease-free survival rate between group A and group B (overall: 55 versus 48%; disease free: 43 versus 42%), but disease-free survival of group C was significantly lesser than that of group A and group B (A versus C: p = 0.022; B versus C: p = 0.040). Tumor invasion of the soft tissue beyond hilar region would not be a prognostic factor in patients who have undergone curative resection for primary lung cancer, although investigation of larger number of cases will be needed to confirm the validity of our conclusion.