Prognostic value of Ki-67 immunolabelling in primary operable breast cancer.

The prognostic value of Ki-67 immunohistochemical labelling was evaluated in 327 operable primary carcinomas of the breast. The follow-up time was up to 4 years (mean 2.7 years). The disease-free survival in Ki-67 positive patients was shorter than in Ki-67 negative patients (P < 0.005). By combining the Ki-67 expression with ER receptors and stage, subgroups with a different disease-free survival were identified. In stage II patients there was a significant difference (P < 0.005) in disease-free survival between Ki-67 positive/ER negative and Ki-67 negative/ER positive patients. In node negative patients there was no such difference. The disease-free survival according to different prognostic factors, stage, ER and node status, were separately examined using a Cox's proportional hazards model. ER (P < 0.0001), the Ki-67 (P < 0.02), tumour size (P < 0.0001) and nodal status (P < 0.006) were independent prognostic factors. We conclude that the potential value of Ki-67 labelling for prognostic evaluation of patients with breast carcinoma is good.