Correlation among [h-3] thymidine, flow-cytometry and proliferating cell nuclear antigen indexes in colorectal tumors

In colorectal cancer and other tumors, proliferating cell nuclear antigen (PCNA) has been found to be a useful marker in immunohistochemical studies of cell proliferation, The presence of a correlation among PCNA labeling index (PCNA LI) and values of cell proliferation expressed by [H-3]thymidine labeling index (TLI) and flow cytometry (FC), the most common techniques used in the evaluation of proliferative activity in colorectal cancer were studied. In 50 operable colorectal cancer patients, TLI, PCNA LI and determination of S-phase fraction by FC were carried out in order to evaluate the correlation among these three indices. A good correlation was obtained between PCNA LI and both TLI (r=0.667; P=0.0001) and percent of cells in S-phase as determined by FC (r=0.819; P=0.0001). It is concluded that PCNA immunohistochemistry can be a reliable marker of the proliferative activity in colorectal rumours. Furthermore, because of its technical simplicity and lower cost it can be more advantageous than TLI or FC.