Prognostic significance of the bromodeoxyuridine labeling index in primary colorectal carcinoma.

The bromodeoxyuridine (BrdU) labeling index was determined in 40 primary colorectal carcinomas by DNA flow cytometry using a BrdU-specific monoclonal antibody. The labeling index, or the fraction of cells in the S-phase of the cell cycle, ranged from 12% to 52%, with a mean of 28% (SEM, 2%). The labeling index in 19 patients was over 30%, which was termed a higher labeling index. There was no significant difference in the labeling index based on the clinical stage of the disease. During the 5-year follow-up after the apparently curative resection, 14 patients died of the disease, 1 died of an unrelated cause, 1 is alive with a recurrence of the disease, and 24 are alive without the disease. The higher labeling index was thus associated with a significantly poorer patient survival (P = 0.03 based on the generalized Wilcoxon test). The present study therefore disclosed that the S-phase fraction of tumor cells thus determined had prognostic significance in primary colorectal carcinoma.