Personalized medicine can cut breast cancer risk

Feb 17 2008

The time has come for breast cancer risk assessment, counseling and genetic testing to move from cancer specialists to the realm of primary care, according to a presentation at the AAAS annual meeting, held this year in Boston.

"A growing body of evidence has documented the benefits of preventive measures for high-risk women including those with mutations in the BRCA1 and BRCA2 genes," said Funmi Olopade, MD, the Walter L Palmer Distinguished Service professor of medicine and director of the Cancer Risk Clinic at the University of Chicago Medical Center. "Referral for cancer-risk assessment and BRCA testing in the primary care setting is a necessary next step towards personalized medicine for women at risk for breast cancer."

Most high-risk women present in the primary care setting, she said. Primary care physicians should learn about the genetics of cancer risk, take a comprehensive personal and family history and advise patients who appear to be at increased risk about the plusses, minuses and limitations of genetic testing and risk-reduction strategies.

Physicians now have enough information to help patients understand the consequences of genetic testing, she added. Studies have found that genetic counseling and testing do not cause adverse psychological effects. There is convincing data on the risk reduction associated with prophylactic surgery—removal of the breasts and or ovaries to prevent cancer in those with known mutations. And preventive measures for those at risk now extend beyond pre-emptive surgery to intensive screening and chemoprevention.

"More than ten years after BRCA1 and BRCA2 were identified as major breast and ovarian cancer susceptibility genes," Olopade added, "primary care providers should embrace genetic risk assessment and BRCA mutation testing."

There is still a great deal that we don't know about these cancer-causing mutations, she added. The frequency and impact of BRCA1 and BRCA2 in various ethnic groups is still poorly understood, with conflicting results clouding the picture. As a consequence, genetic testing is underused by many ethnic groups.

Scientists are still finding new mutations of these genes. Some of these mutations increase disease risk and some may not. These genes may also interact with the environment or with other genes in ways that could modify their effects.

Even the methods of genetic testing can vary. Some tests look only for common mutations; others sequence the entire gene and look for tiny variations.

"There is still a great deal that we do not know about the role of these genes in inherited as well as sporadic breast cancer," said Olopade. "But we do know that mutation of these genes is common in families with hereditary breast cancer and among young women with breast cancer and that when we know a patient has a mutation there are several options to reduce the risk of breast cancer."

No other predictor is as powerful as an inherited mutation in the tumor-suppressor genes BRCA1 and BRCA2. "Our goal," Olopade said, "is to make this knowledge more and more available to patients, and that has to begin in the primary care setting. Only then can we hope to reap the benefits of individualized medicine."