Tumour budding at the deepest invasive margin correlates with lymph node metastasis in submucosal colorectal cancer detected by anticytokeratin antibody CAM5.2.

In the past few years, tumour budding at the invasive margin has been reported as a new risk factor for lymph node metastasis in advanced colorectal cancers, but it is sometimes difficult to detect tumour budding in submucosal colorectal cancer by haematoxylin and eosin staining. We immunohistochemically examined tumour budding at the deepest invasive margin of 56 surgically resected submucosal colorectal carcinomas using anticytokeratin antibody CAM5.2, furthermore checked by AE1/AE3, and determined the relation between tumour budding and clinicopathological factors. Moreover, we used the monoclonal antibody D2-40 for immunohistochemistry to detect lymphatic involvement. Tumour budding was detected in 42 cases (75.0%), and the budding-positive group showed a significantly higher rate of lymph node metastasis (including isolated tumour cells) (16/42 vs 0/14; P=0.004) than the budding-negative group. The sensitivity and negative predictive value of tumour budding alone for lymph node metastasis were superior to those of lymphatic invasion alone. Furthermore, the specificity and positive predictive value of the combination of either lymphatic invasion or tumour budding were superior to those of lymphatic invasion alone. Tumour budding detected immunohistochemically by using CAM5.2 is a newly found risk factor for lymph node metastasis and may help to avoid oversurgery in the future.