Growth fraction in breast carcinoma determined by Ki-67 immunostaining: correlation with pathological and clinical variables.

The growth fractions (GF) of 151 mammary carcinomas were determined in situ by Ki-67 immunoperoxidase staining. A mean value of 14.6% Ki-67-positive tumor cells, with a standard deviation of 11.1, was found. Tumors of histological grades 1 and 2 had a mean GF of 13.1% which was significantly lower (p less than 0.05) than that of grade 3 tumors (mean GF 17.3%). The 14 patients in whom distant metastases appeared after primary staging had a significantly higher (p less than 0.05) GF (21.3%) than the other patients (13.9%). No significant correlation was found between GF and concentration of hormone receptors, lymph node status, tumor size, or patient's age. Our results suggest that immunostaining with Ki-67 could be used as an additional tool to detect breast carcinoma patients with a high risk of developing metastases.