Breast cancer biomarkers predict tamoxifen response

A U.K.-based research team, from the University of Manchester's Paterson Institute for Cancer Research, has found a marker that could highlight those breast cancer patients who aren't likely to respond to tamoxifen, or who will develop resistance to the commonly used drug.

Tamoxifen is used alongside chemotherapy and radiotherapy in estrogen receptor-positive breast cancer, the most common form of breast cancer. It acts by blocking the female hormone estrogen, which helps the tumor to grow, and can improve cancer survival by around a third. However, it is effective in only two-thirds of women with this type of cancer; the other third either respond initially and then develop resistance, or do not respond at all.

The researchers looked at 743 samples of breast cancer tumors from 564 women, some who had taken tamoxifen, and some who hadn't. They focused on the fibroblast cells making up the tissue around the tumor (the stroma), known as cancer-associated fibroblasts (CAFs), and found that the women whose CAFs were low in levels of a protein called pERK were less likely to respond to tamoxifen.

"Testing patients for the pERK flag could help doctors determine whether tamoxifen is an appropriate treatment for their patient or whether alternative therapies should be explored, so saving time and money," says Susann Busch of the University of Manchester.

The next step for the researchers is to look at other biomarkers in fibroblasts, which could help them to develop strategies to overcome resistance.

- read the press release
- see the abstract in PLoS One