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Direct-to-consumer genetic testing does not improve habits in high-risk adults
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Most adults who received elevated direct-to-consumer personal genomic testing to detect risk for single nucleotide polymorphism–based cancer were not more likely to undergo cancer screening or change their lifestyle, according to results of the Impact of Personal Genomics Study.
“One of the major concerns about direct-to-consumer genetic testing is that people who receive data suggesting an elevated risk for cancer may overutilize medical services and overwhelm an already strained health care industry,” Stacy W. Gray, MD, associate clinical professor in the department of population sciences of the division of clinical cancer genetics at City of Hope National Medical Center, told HemOnc Today. “But our study showed that such fears are not likely to be warranted.”
In the study — a prospective longitudinal cohort study designed to examine multiple health outcomes related to direct-to-consumer personal genomic testing — Gray and colleagues administered surveys to 1,042 new customers of 23andMe and Pathway Genomics. The data from these surveys were then linked to individual personal genomic testing results.
Of all the new customers, 71.2% responded to 6-month surveys and 762 had complete cancer-related data and were included in the final analysis.
A majority of individuals reported that learning about their genetic risk for cancers motivated them to get tested; 88% reported they would get tested for colorectal cancer; 95% for prostate cancer; and 94% for breast cancer. None of the individuals tested positive for pathogenic mutations.
A small group of individuals received elevated SNP–based personal genomic testing cancer risk estimates, including 24% with elevated colorectal cancer risk, 24% with elevated prostate cancer risk and 12% with elevated breast cancer risk.
In response to testing results after 6 months, 31% of patients made changes to their diet, 26% changed exercise behavior, 6% changed advanced care planning behavior and 21% changed their use of vitamins/herbal supplements. However, the higher-risk individuals were not significantly more likely to change any of these variables compared with individuals who were at average or reduced risk.
Screening rates following genomic testing were 26% for mammography, 7% for colonoscopy and 19% for PSA testing.
“We found that individuals who are identified as ‘higher risk’ for cancer through direct-to-consumer genetic testing were not more likely to undergo various cancer screenings, including mammography, colonoscopy or PSA testing after direct-to-consumer testing compared with adults who were at a reduced or average risk for cancer,” Gray said.
Researchers may not have observed an increase in screening among those at increased risk because the customers in the study were already “largely compliant with cancer screening recommendations,” Gray said. These findings reassure Gray because there is evidence that people are not undergoing more screening because of direct-to-consumer genetic testing.
Multivariate logistic regression analysis showed a greater proportion of men who received elevated prostate cancer risk estimates changed their vitamin and supplement use compared with those at average or reduced risk (22% vs. 7.6%; adjusted OR = 3.41; 95% CI, 1.44-8.18).
“The results related to supplement use and prostate cancer risk definitely warrant further investigation,” Gray said.
Other predictors of 6-month behavior after genetic testing included baseline behavior with regard to exercise, vitamin/supplement use and mammography, colonoscopy and PSA testing. Further, worse health status predicted diet and vitamin/supplement use, and older age predicted use of advanced planning and mammography, PSA testing and colonoscopy.
The researchers concluded: “Given the fact that SNP–based risk estimates have limited clinical use, patients need to be prepared for the ambiguities inherent in personal genomic testing, and providers need to be prepared to counsel patients about such testing.” – by Melinda Stevens
For more information:
Stacy W. Gray, MD, can be reached at department of population sciences, division of clinical cancer genetics, City of Hope National Medical Center, 1500 E. Duarte Rd., Duarte, CA 91010; email: stagray@coh.org.
Disclosure: Gray reports no relevant financial disclosures. Other researchers report consultant/advisory roles with AIA, Genome Medical, Helix, Invitae, Prudential, Recombine and Roche, as well as honoraria from Illumina.
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