Growth Kinetics of Human Colorectal Carcinoma1

In this study, we investigated the influence of some of the variables of the thymidine labeling index (TLI) in human colorectal carcinoma. These variables were: cell suspensions versus tissue fragments; incubation with 5-fluoro-2'-deoxyuridine; method of tissue procurement; location in the large bowel; and TLI distri bution in different areas of the tumor. Mean TLI values for cell suspensions and tissue fragments were 3.4 (range, 0.1 to 7) and 1 (0.1 to 2.6), respectively. Incubation with 5-fluoro-2'-deoxyuridine significantly reduced tritiated thymidine incorporation. There were no differences in TLI values between biopsy and surgical samples and in different areas of the large intestine. Median TLI of cell suspensions in 47 tumors was 2.25 (0.1 to 10.1). These results show that the TLI of colorectal carcinoma is low and correlates with its slow growth. Cell suspension provides a more representative and unbiased sample than tissue fragments in cell kinetics studies.