CHICAGO ­— Studies show that the risk of breast cancer can be reduced by half through the use of a five-year course of tamoxifen or raloxifene, and also by aromatase inhibitors. Nevertheless, women at high risk of breast cancer have a low acceptance of preventive medicine.

A new study by Mayo Clinic and collaborators at the University of Manitoba and CancerCare Manitoba suggests that when women at high risk are presented with personalized genetic information, they're more likely to take preventative medications to reduce their chance of developing breast cancer. The research involved a new blood test developed by Mayo Clinic to identify women at higher genetic risk for developing breast cancer.

"The practice-changing implications of our study is that by assessing the association between clinical risk factors and selected genetic risk factors, we can potentially provide a novel way to personalize risk and guide decision-making on the patient accepting preventive medications that have been shown to reduce the risk of developing breast cancer," says Sandhya Pruthi, M.D., a general internal medicine physician at Mayo Clinic's Rochester campus.

The results of the study, which have not yet been published, will be presented during a program from 9:45 a.m. to 12:45 p.m. Monday at the American Society of Clinical Oncology annual meeting in Chicago. Dr. Pruthi and her colleagues are among several Mayo Clinic staff members who will present new studies at the meeting, which will be held May 31–June 4.

The primary aim of the study was to determine whether the addition of an individualized breast cancer risk score in addition to current assessment tools would influence patients' decisions to take medications intended to prevent the disease from developing.

The risk score is determined by the blood test developed by Mayo Clinic, which detects single nucleotide polymorphisms (SNP), or what Dr. Pruthi describes as "spelling mistakes," in a patient's DNA. "While individually these SNP risk factors are of little clinical value, when combined as a risk score, they yield a strong risk factor for breast cancer that can be used to personalize a patient's risk," she says.

The risk score increased breast cancer risk estimates for 55.6 percent of study participants. After risk counseling, the participants' intention to take preventive medications changed significantly, with 41.9 percent of those with higher risk scores more inclined to take medication.

"Our study demonstrated that among high-risk women, the polygenic risk score significantly changed the breast cancer estimates and the patient's intent to take preventive medicine," says Dr. Pruthi.

"We are making significant progress toward preventing breast cancer by tailoring treatments to patients based on their unique genetic profiles," she says. "Our hope is that, armed with this specific information, women at risk for breast cancer will make better-informed decisions and accept preventive therapy."

Further study is needed to assess compliance with patients' decisions to go ahead with preventive endocrine therapy.

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Media contact:

• Joe Dangor, Mayo Clinic Public Affairs, 507-284-5005, newsbureau@mayo.edu

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