A survey of members of families affected by hereditary nonpolyposis colorectal cancer shows that only about half choose genetic testing for themselves, according to an article in the March 10th issue of the Archives of Internal Medicine. People who did not participate in testing frequently gave psychological or family concerns as their reason.

Hereditary nonpolyposis colorectal cancer is the most common hereditary form of colon cancer in the U.S., according to information given in the article, accounting for between 1 and 5 percent of cases. Approximately 380,000 Americans carry the responsible allele and have a greater than 90 percent lifetime risk of developing one of the cancers associated with the mutation.

Donald W. Hadley, M.D., and colleagues in the National Human Genome Research Institute, investigated attitudes, intentions, and actual use of genetic testing within families newly identified as affected by the hereditary cancer.

Over 3 years, the research team identified 111 eligible first-degree relatives of 104 adults with hereditary nonpolyposis colorectal cancer and a positive family history. Of the 111 potential participants, 51 percent chose to complete a questionnaire and participate in education and individual counseling sessions that ended with genetic testing.

Participation in these sessions was associated with greater numbers of first-degree relatives already diagnosed with cancer, but no association was found between participation and personal history of cancer.

Baseline questionnaires showed that 64 percent of the participants had heard little about genetic testing for cancers, but most (97 percent) intended to undergo genetic testing. Slightly more than half (51 percent) stated that learning about their children's risk for cancer was the reason they were considering genetic testing, while 39 percent said the potential impact on their health insurance would be the most important reason not to undergo genetic counseling.

Surveys showed that the family members who chose to undergo genetic testing felt their intentions for testing were affected by concerns regarding their ability to handle the emotional and psychological effect on family members.

"Our results suggest that the uptake of genetic testing for hereditary nonpolyposis colorectal cancer among members of high-risk families may be lower than what was originally anticipated and more closely approaches those levels reported in a previous U.S. study," the authors wrote. "Nearly half of the individuals at 50 percent risk of inheriting [the mutation] chose not to participate in the study. A clear understanding as to why such choices were made is unknown."

The authors concluded, "These findings support the inclusion of psychological and psychosocial issues related to genetic testing as part of the informed consent process between health care providers and individuals considering genetic testing."