Angiogenesis at the site of deepest penetration predicts lymph node metastasis of submucosal colorectal cancer

PURPOSE: Intratumor microvessel count has been reported as a useful prognostic factor in patients with cancer of various organs. This study was undertaken to clarify the relation between microvessel count and lymph node metastasis in submucosal colorectal cancer. METHODS: Microvessel count was estimated in 254 invasive tumors that had been resected from patients with submucosal colorectal cancer. Immunohistochemistry with antibodies against CD34 was performed on archival specimens, and microvessel counts were estimated based on the average count of three fields (original magnification, X400) in the most vascular area at the site of deepest submucosal penetration. RESULTS: Microvessel count ranged from 10 to 98, with a median of 40. Lesions with high microvessel counts (greater than or equal to 40) had a significantly higher incidence of lymph node metastasis than those with low microvessel counts (<40; 21.8 percent vs. 6.2 percent). None of the 79 lesions with low microvessel counts and submucosal invasion up to a depth of 1,500 m had metastasized to the lymph nodes. In multivariate analysis, microvessel count was an independent risk factor for lymph node metastasis in submucosal colorectal cancer (P = 0.0026). CONCLUSION: Microvessel count at the site of deepest submucosal penetration can be one of the most useful predictors for lymph node metastasis. Analysis that combines microvessel count and depth of submucosal invasion may predict the occurrence of lesions without lymph node metastasis.