Biomarker predicts tamoxifen breast cancer response

Tamoxifen, in combination with chemotherapy and surgery, is commonly used to treat hormone-responsive breast cancer, but is still only effective in a proportion of affected women. A biomarker identified by researchers at University College Dublin, Ireland, known as CART (cocaine-and-amphetamine-regulated transcript) may make it possible to select and tailor treatment for these women.

In the research published in Oncogene, the team analyzed breast cancer samples from more than 1,000 patients from two groups, whose cancer was hormone-sensitive and had no lymph nodes showing signs of the cancer. They found that the tissues overexpressing CART came from the women who were less likely to respond to tamoxifen, compared with the women whose tissues expressed low levels of CART or no protein at all. Expressing CART seemed to protect the cells from being killed by tamoxifen. According to the researchers, CART has been linked with body weight and the body's response to cocaine and other drugs, but this is the first research to demonstrate a link with breast cancer.

Dr. Donal Brennan, UCD School of Medicine, National Maternity Hospital and joint lead author of the work added: "We clearly demonstrate that both pre- and post-menopausal, early stage breast cancer patients with high CART expressing tumors have a poor outcome and do not respond well to treatment with tamoxifen. Due to this, we believe that they should receive aggressive adjuvant chemotherapy."

Treating only the women likely to respond avoids unnecessary and potentially debilitating chemotherapy, potentially improving their quality of life, and cuts treatment costs. Oncomark, a UCD molecular diagnostics spin-out company, plans to develop a test based on the findings, in order to be able to personalize the treatment for women with breast cancer.

- read the press release
- see the abstract