Public Attitudes Toward Genetic Risk Testing and Its Role in Healthcare

Holly Etchegary

Disclosures

Personalized Medicine. 2014;11(5):509-522. 

In This Article

Does Attitude Toward Genetic Testing Positively Impact Health Behaviors & Outcomes?

Proponents of genomic medicine point to its ability to motivate positive health behaviors and risk-reducing management options among those found to carry mutations predisposing to disease risk.[10,15,61] High expectations have been raised that providing people with DNA risk information could improve health largely by enhancing patient compliance with screening, lifestyle, or other risk-management recommendations (e.g., prophylactic surgery).[61,62] Thus, genomic information could allow for personalized risk prediction that might motivate currently healthy individuals to screen regularly and earlier for disease, take risk-reducing medications and/or adopt lifestyle changes that reduce disease risk (e.g., smoking cessation, dietary changes and increasing exercise behaviors, among others). There is now a large body of literature on the effects of providing genetic risk information on health behaviors, with several reviews published to date.[17,18,63–65] Two trends are notable in this literature: most of the literature to date focused on the provision of DNA risk information related to increased susceptibility for rare Mendelian, single-gene variants, notably inherited cancer, and its effect on screening behaviors; and newer research focuses on the provision (sometimes hypothetical) of personalized DNA risk information in the context of common, chronic conditions (e.g., diabetes, obesity) and its ability to motivate positive lifestyle changes (e.g., dietary changes, exercise and smoking cessation). In general, there is a positive effect of genetic risk information in the former, but no effect or only a transient one in the latter.

Testing for Single-gene Variants

For example, several reviews summarized the evidence for the behavioral impact of genetic risk information on cancer screening in people at risk for inherited breast-ovarian cancer and/or hereditary nonpolyposis colon cancer (HNPCC). Evidence from these reviews generally shows a positive impact of genetic risk information.[17,63,65] For example, women found to carry BRCA mutations were more likely to have a mammogram in the recommended screening interval and more likely to take part in follow-up ovarian cancer screening.[66,67] Similarly, individuals found to be at increased risk for HNPCC were more likely to have a colonoscopy in the recommended screening interval following genetic testing.[68,69] The most recent review on patient compliance[65] summarized the available evidence, reporting that between 70 and 80% of clinically unaffected HNPCC mutation carriers underwent recommended screening following genetic testing. Similarly, carriers of BRCA mutations were more likely to engage in risk-reduction strategies (e.g., mammograms, prophylactic gynecological surgery) than were noncarriers. Noncarriers (of both colon and breast/ovarian mutations) showed an appropriate decrease in screening rates. Indeed, the improvement in screening rates following genetic testing is attributed to the high rates of baseline screening among mutation carriers and appropriately decreased rates of screening in noncarriers following genetic testing.

Testing for Numerous Variants Simultaneously

Newer research is focused on the effects of genetic susceptibility testing for common health conditions 'where the magnitude of increased risk associated with a gene variant is generally much less than in the context of familiar cancer syndromes, meaning the test results will be less predictive and more probabilistic, and where testing likely will reflect risk for multiple health conditions simultaneously'.[17] This sort of testing is predicted to become more common as WGS enters the clinical realm and reduces the cost of genomic profiling.[15,16]

As in the case of public interest in single-gene testing, there is substantial interest in genomic testing for numerous health conditions, with the public often citing its potential to motivate positive health behaviors. For example, Cherkas and colleagues[70] reported that 93% of individuals interested in personal genome testing believed test results would motivate them to adopt a healthier lifestyle. A survey of social network users found almost three-quarters of respondents would talk with their physicians about genomic test results.[71] A recent survey of US residents found 70–88% expressed interest in genomic testing for Alzheimer's disease, breast cancer, prostate cancer and arthritis; most were willing to pay for the test, despite the lack of treatment options for some of the disorders.[72] Two recent studies reported high interest in predictive genomic testing for modest changes in colon cancer risk in both high-risk relatives[73] and primary care patients.[74] In both studies, approximately three-quarters of participants expressed an interest in testing, despite only small to moderate increases in disease risk. Participants noted its potential implications for managing their health.

Does Interest Translate Into More Healthy Behaviors?

Despite these expressed intentions, however, critical reviews find no evidence of sustained behavior change following the provision of genomic risk information.[7,17,18,64] For example, in a Cochrane review, Marteau and colleagues[18] reported on five clinical studies that assessed smoking cessation and found no effect of providing DNA risk information on short term (<6 months) or long-term (>6 months) smoking behavior. Two clinical studies assessing dietary behavior did show a positive impact on dieting, while the two studies assessing exercise behavior did not show any impact of providing individuals with genetic risk disease estimates. In that review, six analog studies showed that providing people with hypothetical DNA risk information effected intention to change behavior only, not the behavior itself. In a more recent review,[65] genetic testing did lead to higher rates of smoking cessation, but only 6 months post-testing; no data were available for compliance after 1 year.[65] Bloss and colleagues explored the psychosocial impacts of genomic risk testing with the Navigenics Health Compass test (a DTC genome-wide profiling test).[75] Of the approximately 2000 respondents who completed follow-up, testing did not result in any measurable changes in anxiety, diet and exercise, or screening behaviors. McBride and colleagues[17] caution, however, that the evidence base to inform whether providing genetic risk information can change diet and exercise behaviors 'is nascent'. They suggest that the single-gene paradigm has influenced which outcome measures are chosen in studies on genetic risk and behavior change. For example, screening behaviors in familial cancer syndromes such as mammography and colonoscopy are by far the most common, with much less attention paid to positive lifestyle changes such as improved diet and exercise or smoking cessation. Until new research that utilizes broader measures of impact is reported, we do not currently know the effect of DNA risk information on healthy behavior.

At present, then, reviews concur that there is little evidence to suggest that the provision of DNA risk information motivates people to change their lifestyle behaviors. However, personalized genetic information based on rare genetic mutations does appear to facilitate appropriate screening behaviors, notably in the inherited cancers.[17,18,63,64] Few studies to date have focused on genetic testing for numerous gene variants simultaneously and the literature thus far suffers from methodological weaknesses that impede our ability to compare across studies.[17,18,64,65] This is a key area for future research, as highlighted below.

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