Clinical relevance of T1-S, an oncogene-inducible, secreted glycoprotein of the immunoglobulin superfamily, in node-negative breast cancer

Axillary lymph node-negative breast cancer patients have a low risk for disease recurrence, and the majority of these patients are cured by surgery alone. However, accurate identification of that 30% of node-negative patients who are at high-risk for relapse and who might therefore benefit from adjuvant systemic therapy has not been possible using traditional histomorphological and clinical prognostic factors alone. Identification of novel tumor-associated molecules may therefore provide a basis for a better understanding of and eventually for an interference with disease progression. We have recently reported on tumor-associated RNA up-regulation of the secreted, soluble T1-S receptor in node-negative breast cancer. In the present study we analyzed the tumor-associated level of the T1-S receptor using semiquantitative immunohistochemistry in a collective of 102 node-negative breast carcinomas to study its clinical relevance. A high T1-S immunoreactivity score indicating T1-S overexpression was observed in 58 of 102 (57%) cases. The T1-S score was independent of the tumor size, type, grade, steroid hormone receptor status, and the proliferation rate determined by monoclonal antibody against KI-67 protein (MIB1) immunohistochemistry. In univariate and multivariate analysis of disease-free survival, a high T1-S score (p = 0.003) and a low MIB1 score (p = 0.001) were the only parameters that were highly significantly associated with an improved disease-free survival period. We conclude that T1-S receptor overexpression is a novel and independent tumor biological factor that may be associated with reduced progression of lymph node-negative breast cancer.