Breast cancer gene

It can predict clinical outcome of tamoxifen, the most widely used treatment for early breast cancer.

Researchers have now found that the ratio of the expression levels of two genes, HOXB13 and IL17BR, can be used to accurately predict the clinical outcome of tamoxifen, the most widely used treatment for early stage breast cancer.

It is the first method, which reliably differentiates between patients who experience disease-free survival and those at a risk for tumor recurrence. The findings also provide new insight into the molecular mechanisms that may contribute to tamoxifen resistance.

Dr. Dennis C. Sgroi from the Pathology Department at Massachusetts General Hospital and Dr. Mark G. Erlander from Arcturus Bioscience, Inc. in Mountain View, California examined the gene expression levels in 60 breast cancer patients who were treated with tamoxifen after their surgery.

They discovered that the ratio of the expression levels of two genes, HOXB13 and IL17BR, accurately predicted whether tumors reoccurred after treatment with tamoxifen.

The researchers also found that when HOXB13 levels were experimentally increased in cells from normal breast tissue cultured in the laboratory, the cells showed obvious morphological changes and became more invasive in response to growth signals.

"This suggests that HOXB13 may directly contribute to tumour invasion and metastasis," Dr. Sgroi explains.

The researchers concluded that HOXB13: IL17BR expression ratio may provide an effective molecular marker for identifying breast cancer patients who will be less likely to successfully respond to tamoxifen and would therefore benefit from an alternative therapeutic strategy for treatment of early stage breast cancer.

"This collaboration has us looking at which patients may benefit from tamoxifen and, as a result, many doors of inquiry have been opened," Dr. Erlander added.