August 29, 2005
58, Number 1
August 29, 2005
Cancer Genetics Program offers assessment,
BY Stacey Jones
Because one out of every three Americans will develop some form of cancer in his or her lifetime, many wonder if they have inherited a risk from family members who are diagnosed with the disease. Patients with family histories of cancer can receive cancer risk assessment and counseling about options for testing and prevention from the comprehensive Cancer Genetics Program, based in the School of Medicine’s Department of Human Genetics.
In the decade since scientists discovered altered genes that increase the risk of some cancers (such as breast, ovarian and colon), the field of cancer genetics has expanded tremendously. Statistically, only about 5–10 percent of cancers have a hereditary basis, but it is important to identify families with an increased risk so their members can reduce that risk or even keep cancer from developing.
The Cancer Genetics Program provides patients with the most current information about inherited risks for cancer and guidelines for screening. Usually referred through their physicians, patients can share their concerns with a genetic counselor at an initial individual session. Over about two hours, patients receive a personalized risk assessment and information about options for genetic testing.
Should a patient decide to pursue genetic testing, the counselor schedules a follow-up visit. Genetic testing for cancer is typically performed on a blood sample, which is sent to a laboratory for analysis.
“A positive result doesn’t necessarily mean cancer will develop in the future,” said Kenneth Loud, co-director of the program and a certified genetic counselor. “But it predisposes people to a greater lifetime risk.”
For example, women who inherit a mutation in one of the breast cancer genes, BRCA1 or BRCA2, are three to seven times more likely to develop the disease than women without a mutation. Moreover, the risk for ovarian cancer is 16–60 percent, compared to less than 2 percent for women without a mutation. Studies have found that the risk for certain types of cancer may be increased depending on which gene is affected. The complexity surrounding the science of inherited cancer risk has led to the development of a whole subspecialty of genetic counseling, according to Loud.
“Colon cancer is an emerging area, with better genetic tests than there were five years ago to detect a risk of developing the disease,” he said, adding he expects scientists will uncover additional “cancer genes,” and subsequent tests will be developed to assess other risks.
The Cancer Genetics Program has an advantage through its association with the Winship Cancer Institute, where prophylactic surgical procedures or medical therapies can reduce the risk of developing inherited cancers. Genetic screening and counseling is important even for those who have already been diagnosed with cancer, Loud said.
“An inherited genetic mutation puts patients at greater risk for a second breast cancer or increases their risk for ovarian or prostate cancer in the future,” he said. “When there is a known mutation of a cancer susceptibility gene in an individual, family members who test negative for the mutation are not at increased risk and can follow general-population cancer-screening guidelines.”
But because of the relatively low risk for inherited cancer and the potential emotional impact of genetic testing, Loud emphasized the value of assessing one’s risk before getting tested. People should probably consider a cancer genetics consultation if they:
• have two or more close relatives (parents, siblings, children, aunts, uncles, nieces, nephews, half siblings, grandparents and grandchildren) with the same or related types of cancer (for example, breast and ovarian; uterine and colon), especially if the cancer was diagnosed before age 50;
• have been diagnosed with cancer themselves before the age of 50;
• have had more than one type of cancer or bilateral cancers (cancer in both breasts, for example);
• have a rare form of cancer, such as male breast cancer;
• come from families with known hereditary cancer syndrome; or
• possess a desire to learn more about hereditary susceptibility to cancer.
For more information about the Cancer Genetics Program, visit www.genetics.emory.edu/genservices/cancer_genetics.php. The site features a referral form for genetic cancer risk and an extensive family history questionnaire.