In this nationally representative sample of US adults, over 15% of participants, representing approximately 34 million US residents, reported having a family or personal history of a BRCA- or Lynch-associated cancer. Women were over-represented in the strong familial risk category even after excluding personal history of breast or ovarian cancer, suggesting that women may report their family histories of cancer more completely than men. Although greater familial risk was associated with increased awareness, referral, and use of genetic testing, the percentages of participants who had heard
of genetic testing, discussed
it with their physician, and received
it were still low, even among those with the strongest familial risk. While many of these individuals may not have family histories strong enough to suggest hereditary cancer syndromes, our findings still suggest that information on genetic testing may not be reaching some appropriate individuals; this is consistent with results from another recent study that reported relatively low rates of awareness and utilization of genetic testing among women at high risk for hereditary breast and ovarian cancer.14
In particular, only 50% of the 5.8 million US residents at highest risk of familial cancer had heard
of genetic testing, and only 15% of these individuals had discussed
testing with a physician. As expected, personal history of cancer was positively associated with testing. Interestingly, Hispanics and African Americans were less likely than non-Hispanic whites to have heard
of genetic testing, but among those who had heard
, Hispanics were more likely to have discussed
testing with their physician, to have been advised to have it, and to have received it compared to non-Hispanic whites.
Very few studies have examined the prevalence of familial cancer risk in the general US population. A previous analysis that used data from the 2000 NHIS reported that approximately 25% of participants had a family history of any cancer,15
but did not examine the association between familial risk and knowledge and use of genetic testing. Ours is one of the first studies to investigate the influence of familial risk of cancer on referral and use of genetic testing in the general population, although some previous studies have examined the association of familial risk with awareness or interest in genetic testing for specific populations. For example, a survey of 600 women from a mammography screening program found that awareness of genetic testing for breast cancer risk was significantly associated with family history of breast cancer, increasing from 35% in the lowest family history risk group to 67% in the group with strongest familial risk.16
Several other studies focusing on general cancer risk or risk of breast or colon cancer have had similar findings.17,18
An analysis of the 2000 NHIS found that awareness of genetic testing was higher for those with any family history of cancer (48.3%) than for those with no family history (37.5%),19
and a subsequent study using data from the 2000 and 2005 NHIS found that women at high risk for hereditary breast and ovarian cancer were more likely than average risk women to have discussed genetic testing with a health professional and to have undergone testing.14
Our finding that individuals with a personal history of cancer were generally more likely to report the genetic testing outcomes is not surprising, and may in fact signal an appropriate approach, as testing should begin with an affected proband.10
In addition, educational efforts in the past decade have promoted improved recognition and counseling of cancer patients about hereditary cancer susceptibility.
Other studies have noted that awareness and use of genetic testing for cancer susceptibility is lower among minority US populations than among non-Hispanic whites.19–23
This may be explained in part by factors such as education, acculturation, and region of residence, although differences remain apparent even after adjustment for many sociodemographic factors.21
To our knowledge, however, this is the first study to report that Hispanics and African Americans who are aware of genetic testing are more likely to discuss it with their physicians or to undergo testing when advised by their physicians. This could be due to self-selection; members of these populations who have heard of genetic testing may represent an unusual and highly motivated subgroup of individuals who have reasons to be particularly concerned about cancer. These findings need to be confirmed in future studies.
A variety of evidence indicates that family history often is not explored or documented by primary care clinicians.6
In a study of over 4,000 primary care visits, family history was discussed in 51% of new patient visits and 22% of follow-up visits, with substantial variation between physicians.24
In a survey of primary care clinicians about breast cancer risk assessment, 30% reported that they do not elicit family history, and 58% reported that they do not communicate family history-based risk to patients.25
Lack of time during visits and problems with current reimbursement policies are two important barriers to collection of family history information.6,26
In addition, primary care physicians may lack confidence in their knowledge of familial risk and risk assessment,25
or they may be discouraged by limited skills about how to use this information to counsel patients.6
Another issue is that patients may not collect or report family history information to their physicians. In a 2004 survey of 4,345 adults conducted by the CDC, 96% of respondents considered family history to be important to their personal health, but only 30% had collected information to develop a family health history.7
Patients may also avoid genetics consultations or genetic testing because they may be worried about privacy issues and potential adverse consequences, such as discrimination in insurance and employment.27
Primary care physicians also report that they lack sufficient knowledge and confidence about referral for genetic services.27–29
In a survey of 82 physicians in a hospital-affiliated health system, including 51 primary care physicians, only 59% reported awareness of the hospital’s cancer genetics program.13
Studies in the United Kingdom have shown that referral guidelines and computerized decision support for general practitioners around familial risk assessment have facilitated appropriate referrals for genetic testing and improved clinician satisfaction with their ability to identify patients for genetic testing and manage familiar cancer risk.30–32
A shortage of adult medical geneticists is another problem that has been reported.27,33
Our study has important clinical and policy implications. Family history has been identified as an important tool for risk stratification and improved disease prevention,3
yet our results suggest that information about genetic testing may not be reaching those at highest familial risk. This may be due to issues with physicians’ assessment of family history as well as their knowledge about familial risk and genetic services. Health professionals’ lack of confidence in interpreting familial patterns of disease and lack of knowledge about genetics may limit their ability to appropriately counsel patients, order and accurately interpret genetic tests, and refer patients for genetic consultation.27
Although a number of questionnaires for assessing family history in clinical settings are available, few have been formally evaluated, and there are no simple, short generic family history questionnaires for use in primary care practice.34
An important priority, therefore, is the development of such tools.2
Computerized tools that collect family history data and utilize clinical decision support to help physicians evaluate risk, provide tailored prevention messages, and make appropriate referrals may be particularly useful.4,6,31,35,36
A major strength of our study is the use of a large, nationally representative dataset. The 2005 NHIS collected detailed information on family history of cancer, including both number of first-degree relatives and age of onset, allowing us to examine strength of familial risk in relation to awareness, referral, and use of genetic testing. We focused on familial risk of BRCA- or Lynch-associated cancers, because these are part of known inherited cancer syndromes for which genetic tests exist.9–12
However, we were not able to conduct separate analyses among participants with family history of each of these syndromes, due to small numbers of the genetic testing outcomes within these subgroups. Our method of estimating familial cancer risk also was limited by the available data. The NHIS Cancer Control Supplement assessed history of cancer only among participants’ first-degree relatives and did not ask about maternal or paternal lineage or whether a mutation had been identified in an affected family member. As a result, the familial risk categories are heterogeneous, and some individuals in the highest category may not have strong family histories suggesting hereditary cancer syndromes. In addition, since the data were cross-sectional, there is no way to determine for certain whether participants’ knowledge of their family history of cancer actually preceded the genetic testing outcomes.
In conclusion, this study provides estimates of the prevalence of familial cancer risk in the general US population and suggests that information about genetic testing is not reaching some at high risk of inherited cancer. Advances in our understanding of genomics will likely make family history-based risk assessment and prevention more important over the coming decades, even for individuals with fewer affected family members. Future studies should explore methods for improving the collection and interpretation of family history information and for increasing knowledge about genetic testing, both for physicians and for patients at high familial cancer risk.