LONG-TERM PROGNOSTIC VALUE OF GROWTH FRACTION DETERMINATION BY KI-67 IMMUNOSTAINING IN PRIMARY OPERABLE BREAST-CANCER

An immunohistochemical determination of the growth fraction (GF) with the Ki-67 monoclonal antibody has been performed in a prospective seri es of 140 patients with primary operable breast carcinoma. GF ranged f rom 0% to 43% Ki-67 stained cells with a median value of 8%. High GF ( > 8%) was significantly associated with axillary node involvement (p = 0.006), aneuploidy (p = 0.008), histologic grade (p = 0.03), and S-ph ase fraction > 5% determined by flow cytometry (p = 0.01). After a med ian follow-up of 6 years, the univariate analysis did not show signifi cant correlation between high GF and worse relapse-free survival (p = 0.10) or shorter overall survival. However, a multivariate analysis on relapse-free survival, performed in 127 comparable patients, showed t hat GF was an independent predictive factor (p = 0.03) together with n odal status (p = 0.00001), age under 45 years (p = 0.0008), and chemot herapy (0.006). In node negative patients, GF was still an independent prognostic indicator (p = 0.002) together with age under 45 years (p = 0.0003). Tumor proliferative activity evaluated by the monoclonal an tibody Ki-67 appears to be an effective indicator of prognosis in brea st cancer and could be of assistance in the decision making of adjuvan t therapy in node negative patients.