Double immunohistochemistry enhances detection of lymphatic and venous invasion in early-stage colorectal cancer.

Lymphatic invasion (LI) and venous invasion (VI) are regarded as important risk factors of nodal disease in early-stage colorectal cancer (CRC) but with variable reporting and poor distinction of these parameters in previous studies. This study examines the application of a double immunohistochemistry (D-IHC) method to help detect and distinguish LI and VI, in comparison with haematoxylin and eosin (H&E) staining, in a clinical series of cases of stage pT1 CRC. The aims were to demonstrate feasibility of this methodology in routine practice and compare rates of LI and VI reporting with and without D-IHC application. D-IHC utilising CAM5.2 with the endothelial marker CD34 and with the specific lymphatic endothelial marker D2-40 was performed on parallel sections from single representative paraffin tissue blocks in 28 cases of stage pT1 CRC from routine clinical practice. D-IHC significantly increased rates of both LI and VI reporting, from 14.3 to 35.7 % and from 14.3 to 28.6 %, respectively. The D-IHC methodology described is technically feasible in routine practice and potentially offers a more sensitive and robust assay for detection and distinction of LI and VI in early CRC pathology reporting. The reproducibility and clinical significance of enhanced LI and VI detection by this method and the relative importance of LI and VI in this clinical setting require further study.