Preoperative CA 15-3 concentrations predict outcome of patients with breast carcinoma

CA 15-3 is a breast-associated mucin that is elevated in the majority of breast carcinoma patients with distant metastases. Currently, the main application of this marker is in monitoring and detecting recurrences in patients with diagnosed breast carcinoma.

Preoperative serum concentrations (prior to excision of the primary tumor) of CA 15-3 were measured in 368 patients undergoing potentially curative surgical treatment for early breast carcinoma. These results were compared with prospectively recorded clinicopathologic characteristics and patient outcome data.

A weak but significant positive association was found between CA 15-3 concentrations and both tumor stage and the number of involved axillary lymph nodes but not between CA 15-3 concentrations and estrogen receptor status. Patients with high concentrations of CA 15-3 had a significantly worse prognosis than patients with low concentrations. Using an optimum cutoff value of 30.38 U/mL, the probability of disease free survival at 5 years was 44% in patients with high CA 15-3 levels compared with 65% in patients with low CA 15-3 levels (P = 0.002, Mantel-Cox log rank test). The corresponding probabilities for overall survival were 67% and 83%, respectively (P < 0.001). The association of preoperative CA 15-3 levels with outcome was maintained in multivariate survival analysis and was not explained by the association between CA 15-3 and tumor size or lymph node burden. The relation between CA 15-3 and outcome also was found within some patient subgroups identified by traditional prognostic factors (axillary lymph node positive patients, patients with primary tumors >2 cm in greatest dimension, and patients with estrogen receptor positive tumors).

Preoperative serum concentrations of CA 15-3 appear to have a significant relation to outcome in patients with early breast carcinoma and may have a role in the rational selection of patients for appropriate adjuvant treatments. To the authors' knowledge, CA 15-3 thus is one of the first circulating markers shown to be an independent prognostic indicator in patients with breast carcinoma.