Cell cycle parameters and DNA ploidy in colorectal carcinomas

Seven patients with colorectal adenocarcinoma and one with squamous cell carcinoma of anorectal region were infused preoperatively with iododeoxyuridine (IUdR) and bromodeoxyuridine (BrdU) in sequence (100 mg/m² × 1 hr each with 1-hr interval in between) to label S-phase cells. The tumor biopsy specimens were embedded in glycolmethacrylate and 2-μm thick sections were treated with two monoclonal antibodies which permitted the identification of cells which incorporated IUdR only, BrdU only, both IUdR and BrdU, or neither IUdR or BrdU. The labeling index of tumors varied from 17.3 to 35.6% (mean = 25.78 ± 6.162), duration of S-phase ranged from 14.0 to 23.9 hr (mean = 18.73 ± 3.712), and total cell cycle time ranged from 39.4 to 123.4 hr (mean = 76.78 ± 24.165). The architecture of the tumor was well preserved and a variable number of DNA synthesizing mononuclear cells were identified within and around the tumor. Image analysis of Feulgen-stained smears of the tumors was done to measure the DNA content of seven tumor samples. Each tumor was found to be hyperdiploid with multiple modal values. The studies described here demonstrate the feasibility of performing cell cycle kinetic measurements on gastrointestinal tumors which have been labeled in vivo. The ability to perform these measurements on tumor biopsies allows the avoidance of artifacts introduced when solid tumors are disaggregated in vitro for study.