RSNA: Future of breast cancer treatment may rely on genetic testing

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CHICAGO--Genetic considerations should be factored into the clinical treatment and screening for breast cancer, said Bruce G. Haffty, MD, during the annual oration in radiation oncology at the Radiological Society of North America (RSNA) conference on Wednesday.

Haffty, chair of the department of radiation oncology at UMDNJ-Robert Wood Johnson Medical School in New Jersey, explained that genetically inherited disorders are characteristically the result of relatively low-frequency dominant mutations -- including BRCA1 and BRCA2, two proven breast cancer susceptibility genes -- and that carrying these mutations increases an individual’s likelihood of manifesting the disease.

Single nucleotide polymorphisms, a genetic variant appearing in at least one percent of the population, warrants further research in terms of breast cancer vulnerability, he said.

“These polymorphisms can have huge effects on the development of cancers, women's susceptibility and treatment response,” said Haffty. "Humans are essentially identical in their DNA. These polymorphisms, however, allow for [individuals] to be very different, giving us unique susceptibility to disease and responses to treatment.”

Genotyping of polymorphisms has already entered the area of clinical practice, he said. About 10 percent of the population is unable to  metabolize the breast cancer drug tamoxifen into its active form once in the body as the result of carrying a certain polymorphism. Therefore, it would not be beneficial for these patients to be treated with this medication.

He questioned how genetic testing's role might change given the newly released guidelines on breast imaging by the U.S. Preventive Services Task Force (USPSTF) that suggest no routine mammography screening for women in their 40s.

He said the task force itself has recognized the need to make considerations that support providing genetic testing to particular patients. He said he hopes these will include individuals with certain polymorphisms more frequently.

Haffty’s presentation depicted a future for imaging in which the patient is screened for the genetic factors that can be attributed to higher breast cancer risk. Once those polymorphisms are discovered, the screening process can be determined for each patient.

While this field is considered to be in its infancy, he encouraged other physicians to become involved in further studies.

“It is with single nucleotide polymorphisms that we will see over time that we can personalize medicine to optimize [patient] care,” he concluded.