Familial risk of cancer and knowledge and use of genetic testing

Abstract

Background: Identification of genetic risk factors for common diseases, including cancer, highlights the importance of familial risk assessment. Little is known about patterns of familial cancer risk in the general population, or whether this risk is associated with knowledge and use of genetic testing.

Objective: To examine the distribution of familial cancer risk and its associations with genetic testing in the United States.

Design: Cross-sectional analysis of the 2005 National Health Interview Survey (NHIS).

Participants: 31,428 adults who completed the NHIS Cancer Control Supplement.

Main measures: Familial cancer risk was estimated based on the number of first-degree relatives with a breast and ovarian cancer syndrome (BRCA)- or a Lynch-associated cancer, age of onset (<50 or > or = 50 years), and personal history of any cancer. Outcomes included having heard of genetic testing, discussed genetic testing with a physician, been advised by a physician to have testing, and received genetic testing.

Key results: Most adults (84.5%) had no family history of BRCA- or Lynch syndrome-associated cancer; 12.9% had a single first-degree relative (5.3% with early onset); and 2.7% had > or = 2 first-degree relatives. Although 40.2% of adults had heard of genetic testing for cancer risk, only 5.6% of these individuals had discussed testing with a physician, and of these 36.9% were advised to be tested. Overall, only 1.4% of adults who had heard of genetic testing received a test. Familial risk was associated with higher rates of testing; 49.5% of participants in the highest risk group had heard of testing, of those 14.8% had discussed it with their physician, and 4.5% had received genetic testing.

Conclusions: These nationally representative data provide estimates of the prevalence of familial cancer risk in the US and suggest that information about genetic testing is not reaching many at higher risk of inherited cancer.