Scientists from the Harvard Stem Cell Institute (HSCI), the Brigham and Women's Hospital (BWH) and the Dana-Farber Cancer Institute (DFCI) have discovered a biomarker that exists in the normal breast tissue of women, which can be used to determine whether they are at high risk of developing breast cancer later in life.

In a study featured in the journal Cancer Research, researchers Kornelia Polyak from the HSCI and Rulla Tamimi from the BWH led their colleagues in identifying new ways to find out the susceptibility of certain individuals to developing breast cancer.

Their paper builds on Polyak's earlier work where she found that women with a high risk to develop cancer and those who did not have a baby before they turned 30 years old had high amounts of progenitor cells in their mammary glands.

Polyak, Tamimi and their team examined data collected from 302 women diagnosed with benign breast disease who took part in the Nurses' Health Study and the Nurses' Health Study II. They compared tissue samples taken from 69 participants who had cancer to tissue samples from the rest of the group who did not develop the malignancy.

The team discovered that participants who had high levels of a molecular marker known as Ki67 were five times more susceptible to developing cancer. Ki67 was found in mammary epithelium cells, which are located in the lobules and mammary ducts of women. Most types of breast cancers are known to begin in these particular tissues.

While doctors already use levels of Ki67 present in breast tumors to help them determine the appropriate treatment for patients, this latest study is the first instance where medical researchers were able to associate the molecular marker to healthy tissue, which can be used to predict the likelihood of individuals to develop cancer.

Tamimi pointed out that doctors currently have a difficult time in finding out if a patient has a low or high risk of developing breast malignancies. Being able to identify those who are at a high risk for the cancer would allow researchers to come up with individualized screening as well as strategies on how to lower these risks.

Photo: Ed Uthman | Flickr