16. Cancer testis antigen (CTAg) expression is commonly observed in early-stage triple negative (TN) breast cancer

Abstract

<h3>Background</h3> There are currently limited treatment options for triple negative (TN) breast cancer which has poor prognosis. Expression of CTAgs is confined to testis and cancer cells, making them ideal targets for specific vaccine treatment. We examined the expression of four CTAgs (MAGE-A3, NY-ESO-1, MAGE-A1, and MAGE-C1) in TN breast cancer to evaluate their potential as targets for vaccine treatment and for any association between CTAg expression and histopathological prognostic factors. <h3>Methods</h3> 39 patients with confirmed early-stage TN breast cancer resected at Austin Hospital and The Northern Hospital between 2001 and 2009 were included. Immunohistochemical staining was performed on tissue microarrays of FFPE tissues. The proportion of tumours expressing CTAgs, percent of tumour area stained, and intensity of staining (semi-quantitative) were evaluated. Associations between CTAg expression and histopathological prognostic factors were tested using Fisher's exact tests. <h3>Results</h3> 82% (95%CI 0.69-0.95) of tumours expressed one or more CTAg, with co-expression of >2 CTAgs in 59% of tumours. The most frequent CTAgs expressed were MAGE-A3 and NY-ESO-1 (59% and 51% of tumours, respectively). Staining of >50% of tumour area and higher staining intensity was most frequently observed in tumours expressing MAGE-A3 and NY-ESO-1. There was a positive association between CTAg expression and tumour grade (<i>p</i>=0.02), but no association with T stage, nodal involvement, multifocality, lymphovascular invasion or necrosis. <h3>Conclusions</h3> CTAg expression is very common in early-stage TN breast cancer. There was a positive association between CTAg expression and tumour grade. Development of vaccines against these CTAgs may have benefit in treatment of TN breast cancer.