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.

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