TFF3 breast biomarker has darker side

A biomarker that has been linked with a good prognosis in early-stage breast cancer has turned out to have a Jekyll and Hyde-like personality--its increased expression at a later stage ties in with breast cancer invasion and metastasis, which is not good for the patient.

The trefoil factor 3 (TFF3) protein has a role in normal breast tissue, where it protects and maintains cells. In low grade (less severe) tumors, increased expression of TFF3 generally points to a good outcome for patients. In a study published in the American Journal of Pathology, researchers confirmed that there were increased levels of TFF3 in most of the tumor samples they looked at, including the benign ones. However, there was a clear link between high levels of the protein and cancers that were more likely to be invasive, or to spread to other parts of the body.

The researchers also looked at the potential of TFF3 as a biomarker of disease invasion and metastases into the lymphatic system, and found that it had a greater predictive power than other markers analyzed.

"Our study reinforces the view that TFF3 expression merits evaluation as a prognostic biomarker and as a predictive marker of response to therapy," concludes lead investigator Felicity E.B. May, Ph.D., of the Northern Institute for Cancer Research and the Department of Pathology at Newcastle University, U.K. "It is probable that its malign effects will be mitigated by adjuvant endocrine therapy in women with hormone-responsive cancers. However, the usefulness of TFF3 as a marker of hormone responsiveness needs to be evaluated."

This leaves the researchers with a paradox: a single protein that is linked with the health of normal breast tissue, good outcomes in early-stage cancer, and poor outcomes in late-stage cancer. As May says, more research is needed to clear up the dual personality of this marker and confirm how useful it may be.

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