A close association between alteration in growth kinetics by neoadjuvant chemotherapy and survival outcome in primary breast cancer.

Few surrogate markers are available for predicting the survival benefit from chemotherapy in primary breast cancer. We examined tumor growth kinetics by assessing cytokeratin 18 neo-epitope (CK18NE), an apoptosis marker detected by M30 antibody and Ki-67 antigen, a proliferation marker detected by MIB-1 antibody in 72 primary breast cancer patients who underwent pre-operative anthracycline-based chemotherapy. Increase in M30 index and decrease in MIB-1 index after the exposure of 2 to 4 cycles of chemotherapy correlated significantly with pathological tumor response. Univariate survival analysis, conducted in the subgroup of 42 patients who underwent CAF (cyclophosphamide, adriamycin and 5-FU) therapy alone, showed that the patients with the high levels of M30 index (>35 counts/1000 tumor cells) and the low levels of MIB-1 index (<140 counts/1000 tumor cells) after chemotherapy had a remarkably favorable prognosis as compared with patients in other categories. In addition, the alteration in growth kinetics by the treatment showed a significant prognostic value. Multivariate analysis also confirmed that the post-treatment growth kinetics was an independent prognostic indicator. These findings suggest that the alteration in growth kinetics revealed by CK18NE and MIB-1 might be a surrogate marker for predicting the survival benefit from chemotherapy in primary breast cancer.