Annette Patterson

Though genetic testing requires little more than a simple blood  draw, learning about one’s genetic status may open a Pandora’s box of personal  and familial issues. Grappling with the sometimes unexpected implications of  such testing can challenge even the closest of families. For this and other  reasons, the American Society of Clinical Oncology recommends that testing be  done only within the context of genetic counseling. 

Working with genetics professionals, individuals, and families  explore the possible consequences of genetic testing and develop realistic  expectations of what may or may not be learned in the process. Appropriate  candidates for genetic testing include individuals with one or more of the  following: early-onset cancers (usually under age 50 for adult onset syndromes),  more than one cancer diagnosis, a strong family history of cancer or the  presence of rare cancers, such as male breast cancer and fallopian tube  cancer.

In the ideal case, testing provides information that either  confirms high-risk status or rules out the presence of a genetic alteration  found in other family members. For those who test positive, increased screening  may detect cancer at an early stage, allowing patients to avoid aggressive  treatments like chemotherapy. In other cases, cancer may be prevented altogether  using prophylactic (preventive) surgeries. Because gene alterations often  predispose individuals to many types of cancer, identifying genetic status early  on can drastically affect long-term outcomes.

As helpful as genetic testing may be, it occasionally raises more  questions than it answers. Results in some cases may be uninformative or  ambiguous, as in families with a strong history of cancer who receive “negative”  test results. These families may actually carry an alteration in a gene yet to  be discovered or one that cannot be detected using current technologies. In  other cases testing may reveal a genetic variant of unknown significance,  leaving cancer specialists unable to interpret results or accurately assess  cancer risk. Such results make it harder to determine the best course of action  and do little to alleviate worry.

Genetic testing is now available for dozens of hereditary cancer  syndromes, most of which are caused by alterations in genes that suppress tumor  growth. To date the most commonly requested test is for BRCA1 and BRCA2.  Alterations in these two genes predispose individuals to breast, ovarian and  other cancers, and are found more frequently in families of Ashkenazi Jewish  descent.

Among female carriers, BRCA alterations confer a lifetime breast  cancer risk of up to 85 percent and an ovarian cancer risk of up to 50 percent.  Male carriers also have increased risk for breast, prostate and other cancers.  Other genetic tests commonly requested include analyses for two colon cancer  syndromes: hereditary nonpolyposis colon cancer (HNPCC) and familial adenomatous  polyposis (FAP). Both syndromes are associated with a significantly increased  risk for colon cancer (80 percent and virtually 100 percent, respectively), as  well as other cancers.

The cost of genetic testing ranges from a few hundred to several  thousand dollars, depending upon the number of genes tested and the number of  sites analyzed within a given gene. Because three recurrent mutations account  for the vast majority of BRCA-related cancers in Ashkenazi Jews, testing is  abbreviated and much less expensive than that for the general population ($460  as opposed to $3,120). For appropriate candidates, insurance often covers most  or all of the cost of genetic testing.

To find a genetic counselor in your area, visit the National  Cancer Institute’s website at 

Articles

Learning about one's genetic status may open a Pandora's box of personal and familial issues.

Annette Patterson

To Know or Not To Know

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