Accuracy and prognostic impact of a vessel invasion grading system for stage IA non-small cell lung cancer

Despite the recognition that lymphatic and blood vessel invasion is an important prognostic factor in lung cancer, there is no common definition for pathological evaluation of vessel invasion. The aim of the present study was to determine whether D2-40 immunostaining can increase the accuracy of detection of lymphatic vessel invasion and whether our new grading system of vessel invasion by "degree" could be used instead of conventional evaluation by "presence" for pathological stage IA non-small cell lung cancer (NSCLC).

The vessel invasion classification was re-evaluated in 221 recent paraffin-embedded sections of p-stage IA NSCLC stained by Hematoxylin-Eosin (HE), Elastica-Van-Gieson (EVG), and D2-40.

After re-assessment using D2-40 immunostaining, 41.2% (31 of 75) of ly1 cases by HE/EVG changed to ly0, and 14.9% (17 of 114) of ly0 cases by HE/EVG changed to ly1. Overall, 4 of 28 ly2 cases on conventional staining were changed to ly1, and 2 were changed to ly0 using D2-40 immunostaining. When the patients were divided into two groups by the presence of vessel invasion (v/ly0 vs. 1, 2, 3), there was no significant difference in cancer-specific survival (p=0.1107, 0.0875, respectively), while when they were divided according to degree of vessel invasion (v/ly0, 1 vs. 2, 3), there was a statistically significant difference (p=0.0038, p=0.0002, respectively). On multivariate analysis, lymphatic vessel invasion had a significant impact on cancer-specific survival (p=0.0061).

Our results suggest that D2-40 immunostaining provides a precise diagnosis of lymphatic vessel invasion, and our new grading system of vessel invasion by "degree" is accurate and has prognostic value in early lung cancer.