Immunohistochemical assessment of lymphovascular invasion in stage I colorectal carcinoma: prognostic relevance and correlation with nodal micrometastases.

Several studies have suggested that the presence of occult nodal metastases (micrometastases) is related to adverse clinical course in stage I colorectal carcinoma. Herein we analyzed the correlation between nodal micrometastases and lymphovascular invasion (LVI) or lymphatic vessel density (LVD) in a series of stage I colorectal carcinomas; the cohort included cases characterized or not characterized by disease progression during the follow-up. In these cases, LVI and LVD were evidenced through the immunohistochemical detection of the specific marker for lymphatic vessels, D2-40. LVI was significantly more frequent in colorectal carcinomas characterized by the presence of micrometastases (P<0.0001), high peritumoral LVD (P<0.0001), and disease progression (P<0.0001). The analysis for progression risk indicated that nodal micrometastases and LVI were significant, negative, independent prognostic parameters associated with shorter disease-free survival of stage I colorectal cancer (P=0.0001; P=0.0242). In conclusion, in this study we demonstrated for the first time that LVI is significantly associated with nodal occult metastases in stage I colorectal carcinoma. In the light of its significant, independent, prognostic value in this neoplasia, the detection of LVI may represent a faster and cheaper tool compared with the time-consuming evaluation of micrometastases to select high-risk patients who may benefit from adjuvant systemic treatment. Furthermore, the assessment of LVI may be applied to establish the likelihood of nodal involvement from carcinomas treated with conservative local excision techniques, which provide no regional nodes for histologic examination.