Expression of cancer-testis antigen CT7 (MAGE-C1) in breast cancer: an immunohistochemical study with emphasis on prognostic utility.

High expression of the cancer-testis antigen CT7, also referred to as MAGE-C1, has been recently described in a variety of malignant tumors, including breast carcinoma. To our knowledge, no data concerning the prognostic utility of CT7 expression in breast cancer are available. In this retrospective study, we evaluated the relationship between CT7 immunoreactivity and clinicopathological parameters as well as relapse-free survival (RFS) and metastasis-free survival (MFS) of 124 women with invasive breast cancer. A positive CT7 status, defined as immunoreactivity in more than 50% of tumor cells, was found in 18% of cases and correlated significantly with high tumor grade (p=0.004), but with no other clinicopathological parameter. In a univariate analysis, CT7 status showed an association with RFS by trend (p=0.107; relative risk [RR]: 1.85) and a significant association with MFS (p=0.043; RR: 2.02). In a multivariate analysis, tumor grade, stage, nodal status, angioinvasion, HER2 expression as well as estrogen and progesterone receptor expression were identified as significant independent prognostic factors of RFS and/or MFS. In this respect, CT7 expression showed a weak, statistically not significant trend towards an independent prognostic relevance concerning prediction of MFS (p=0.147; RR: 1.95). Our data suggest that estimation of CT7 immunoreactivity is of limited prognostic usefulness in breast cancer. It may provide additional information concerning assessment of MFS in selected cases.