ASSESSMENT OF KI-67-DERIVED TUMOR PROLIFERATIVE ACTIVITY IN COLORECTAL ADENOCARCINOMAS

Analysis of tumor growth fraction (TGF) has become essential as cell c ycle-directed modalities have been increasingly used for the treatment of solid neoplasms. We studied TGF in fresh tissue samples from 74 su rgically resected colorectal carcinomas (50 colon and 24 rectum; 44 me n and 30 women) by flow cytometry (FCM) and by immunostaining using Ki -67 monoclonal antibody. In 12 cases, samples of uninvolved colonic mu cosa adjacent to tumor (transitional mucosa) and samples of normal muc osa (at least 5 cm away from tumor) were available for growth fraction analysis. The mean Ki-67 and S-phase values were 17.1% (range, 0-60%) and 17.5% (range, 3-39%), respectively. The mean percentage of Ki-67 positivity in tumor samples from women was significantly lower than th at in samples from men (P = 0.001). Ki-67-derived TGF values, however, did not correlate with patient age, lymph node status, or tumor size, site, stage, degree of differentiation, or DNA ploidy. The correlatio n between Ki-67-derived and FCM-derived TGF values was statistically s ignificant (P = 0.001) but marginal (R = 0.35). In both transitional a nd normal colonic mucosa samples, Ki-67 positivity was mainly confined to the lower half of the crypts, and their growth fraction values wer e significantly lower than those of tumor tissue; however, there was n o difference in values between transitional and normal mucosae. Our re sults indicate that Ki-67-derived TGF does not correlate with known pr ognostic factors for colorectal carcinoma; however, long-term follow-u p information will be necessary to define the clinical value of Ki-67 staining.