Serum tumor marker CA 15.3 and stage are the two most powerful predictors of survival in primary breast cancer.

The purpose of this prospective study was to evaluate the usefulness of tumor marker CA 15.3 determined at the time of primary diagnosis as a prognostic factor in breast cancer. The power of CA 15.3 to predict survival was compared to established prognostic markers, namely stage, grade, receptor status, and histological subtype. CA 15.3 was abnormal (> or = 30U/ml) in 31 (11%) of the 272 patients. During the median follow-up of 9.8 years, 83 (31%) of the patients died of breast cancer. The disease-specific survival at 5 years were 86 and 45% with normal and abnormal CA 15.3 values, respectively (p < 0.00005). When using univariate analysis, tumor size, nodal status, M status, stage, tumor grade, and CA 15.3 were significantly related to patient outcome. In the regression analysis, stage (p = 0.00023) and CA 15.3 (p = 0.00006) were prognostic factors for survival. These results indicate that CA 15.3 can predict survival in primary breast cancer.