Mammaglobin is associated with low-grade, steroid receptor-positive breast tumors from postmenopausal patients, and has independent prognostic value for relapse-free survival time.

Abstract

The tumor mRNA expression levels of mammaglobin, a novel breast-specific and breast cancer-associated marker, were correlated with disease outcome in 280 patients with primary breast cancer. Mammaglobin expression levels were assessed by quantitative reverse transcriptase polymerase chain reaction in frozen tumor tissue from breast cancer patients with a median age of 60 years (range, 30 to 88 years) and a median follow-up of 85 months (range, 2 to 169 months). High expression levels were associated with low-grade tumors (P =.018), with positive estrogen and progesterone receptor status (P <.001), and postmenopausal status (P =.010). In the analysis of all patients, low tumor mammaglobin expression levels predicted an early relapse both in Cox univariate (hazard ratio [HR], 0.52; 95% CI, 0.34 to 0.79; P =.002) and multivariate regression analyses corrected for the traditional prognostic factors (HR, 0.55; 95% CI, 0.35 to 0.88; P =.012). The association of mammaglobin expression with the rate of relapse was particularly favorable in patients who received adjuvant tamoxifen treatment (HR, 0.35; 95% CI, 0.17 to 0.71; P =.004). These results demonstrate that the assessment of the tumor mRNA expression level of the breast-specific protein mammaglobin could be useful to stratify patients for individual adjuvant treatment strategies.