Ca15.3 corresponds to the MUC1 gene product, similar to epithelial membrane antigen. The monoclonal antibody is available commercially under the designation CA 15-3 MoAb and stains formalin-fixed tissue after antigen retrieval.

Immunohistochemical expression

Diagnostic utility

Serum CA15.3 is more sensitive than CEA in the detection of recurrent breast carcinoma2.


1 Delsol G, New antibodies and new applications of old antibodies in the diagnosis of hematolymphoid neoplasms. In Immunohistochemistry Long Course, Nice, October 18-23, 1998.

2 Colomer R, Ruibal A, Genolla J, et al. Circulating CA 15-3 levels in the postsurgical follow-up of breast cancer patients and in non-malignant diseases. Breast Cancer Res Treat 1989; 13:123-33

Kufe D, Inghirami G, Abe M, et al. Differential reactivity of a novel monoclonal antibody (DF3) with human malignant versus benign breast tumors. Hybridoma 1984; 3:223-32

Ho JJ, Chung YS, Yuan M, et al. Differences in expression of SPan-1 and CA15-3 antigens in blood and tissues. Int J Cancer 1992; 52:693-700


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