Proliferative activity as revealed by Ki-67 in uterine adenocarcinoma of endometrioid type: comparison of tumours from patients with and without previous oestrogen therapy.

The Ki-67 antibody recognizes a nuclear antigen related to cell proliferation, which in some studies has been shown to reflect the aggressiveness of tumours. The percentage of Ki-67-positive cells was estimated by immunohistochemistry on frozen tissue sections from 73 adenocarcinomas of endometrioid type (EC) (40 tumours from patients who had never received postmenopausal oestrogen treatment and 33 tumours from patients with previous postmenopausal oestrogen treatment). The Ki-67 content was weakly but significantly (P < 0.05) correlated to nuclear grade, architectural grade, and crude mitotic count, but not to stage or progesterone receptors. Ki-67 expression in EC from patients with previous oestrogen therapy was much lower (median 10 per cent Ki-67) than that in EC from patients who had never received oestrogen treatment (median 24 per cent Ki-67), suggesting that a prognostic cut-off point may be different in tumours from the two groups of patients. The mitotic count discriminated the two groups of patients to a much smaller degree. It is also shown that a quick qualitative Ki-67 estimate can replace the time-consuming quantitative assessment.