Budding as a risk factor for lymph node metastasis in pT1 or pT2 well-differentiated colorectal adenocarcinoma

Lymph node metastasis is an important indicator of tumor stage and prognosis in pT1 and pT2 colorectal adenocarcinomas. Lymphovascular invasion is an established risk factor of lymph node metastasis, whereas budding at the invasive front of tumors is also reported to correlate with lymph node metastasis. We examined whether the coexistence of lymphovascular invasion and budding provides any better information than lymphovascular invasion alone in the prediction of lymph node metastasis of pT1 or pT2 well-differentiated colorectal adenocarcinomas.

Surgically resected specimens of 101 pT1 or pT2 well-differentiated colorectal adenocarcinomas were studied. Using sections stained with hematoxylin-eosin, we examined lymphovascular invasion and budding according to Morodomi's definition.

Lymphovascular invasion was present in 39 lesions (38 percent), whereas budding was found in 42 lesions (41 percent). Budding was more frequently detected in pT2 tumors than in pT1 tumors. The presence of budding significantly correlated with lymphovascular invasion. Sensitivity, specificity, positive predictive value, and negative predictive value of lymphovascular invasion alone for lymph node metastasis were 79, 76, 34, and 96 percent, respectively, whereas those of the combination of lymphovascular invasion and budding (either lymphovascular invasion or budding) were 93, 52, 24, and 98 percent, respectively.

Because the risk of lymph node metastasis in pT1 or pT2 well-differentiated colorectal adenocarcinomas having neither lymph node metastasis nor budding is very low, budding in combination with lymphovascular invasion seems to be a simple and inexpensive pathologic marker in predicting lymph node metastasis. Therefore, the presence or absence of budding should be examined in the routine pathologic diagnosis of pT1 or pT2 well-differentiated colorectal adenocarcinomas.