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.