Biomarker predicts which breast cancer patients will respond to tamoxifen

Women who suffer from estrogen receptor-positive breast cancer are widely prescribed anti-estrogen drugs, especially tamoxifen. The problem is that as many as one-third of the women on tamoxifen fail to respond to the drug. A group of researchers say they have found a way to predict which breast cancer patients are not likely to respond to tamoxifen and should be given something else, saving time and resources in treatment--and possibly saving lives, as well.

The biomarker they've found is a protein called Stat5. Those who have it stand an increased likelihood of responding to tamoxifen. On the other hand, women treated with tamoxifen whose tumors lacked active Stat5 had up to a twentyfold increased risk of dying from breast cancer, according to the researchers.

"Identification of predictive biomarkers present in breast cancer will lead to improved individualized therapies tailored specifically towards each woman's cancer," Hallgeir Rui, oncology professor at Kimmel Cancer Center at Thomas Jefferson University in Philadelphia, said in a news release. "Absence of the active form of Stat5 could help identify a group of patients unlikely to respond to tamoxifen so they may be offered alternative and more aggressive treatments."

The researchers say more work needs to be done, but they're confident in Stat5 as a biomarker. "The team is moving forward with plans for a randomized, prospective study with larger patient numbers to further evaluate the utility of Stat5 in managing and treating breast cancer," lead researcher Amy Peck said in a release.

- take a look at the release from Thomas Jefferson University
- and an abstract of the study in the Journal of Clinical Oncology