In vivo determinations of labelling index of metastatic colorectal carcinoma and normal colonic mucosa using intravenous infusions of bromodeoxyuridine

In vivo determination of the labelling index of metastatic colon carcinoma was performed in 14 patients following intravenous infusion of bromodeoxyuridine (BrdU), at doses of 100 and 50 mg/M². No toxicity was seen. Labelled cells were detected by an immunohistochemical technique using a monoclonal antibody to BrdU. Labelling was uniform and highly specific with good preservation of morphology. Labelling index values ranged from 15.0–40.6% for metastatic lesions and 3.6%–20% for normal colonic mucosa, with mean values of 24% and 11%, respectively. This represents a useful new method for in vivo labelling index determination in solid tumors.