Objectives The emergence of genetic and genomic testing has led to an era of precision medicine, particularly within developed countries. Predictive genetic testing is a primary prevention method that uses high-susceptibility gene variants to flag certain cancers for rapid intervention, thereby reducing mortality and morbidity. Such tests have potential to help patients make better healthcare decisions. Although predictive genetic testing is available in clinical settings for patients with family history of CRC, it is less clear how results will improve patient screening behaviour.
This systematic literature review aimed to synthesise evidence to assess the impact of personalised genetic risk information on decisions to undergo colorectal cancer screening in asymptomatic adults.
Method MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, PsychINFO, and ProQuest (Health and Medicine) databases were systematically reviewed. NHS Evidence and Clinical trials.gov websites were also searched, whilst Clinical Genetics, Journal of Genetic Counselling, Medical Decision Making, and Public Health Genomics journals were hand searched for relevant articles. Studies were selected on inclusion/exclusion criteria. Critical appraisal methods were used to critique the quality of eligible studies, followed by a descriptive and narrative synthesis to synthesise evidence.
Results 3843 studies were screened by title and abstract, followed by full-text screening of 27 potential studies. This review identified 12 studies that addressed the research question and met inclusion/exclusion criteria. Studies were heterogeneous in study design and focused on different population groups that were either high-risk or average risk. Overall, high-risk asymptomatic individuals that received genetic testing and counselling followed CRC screening recommendations after receiving positive test results.
This review identified several gaps related to research design, standardisation of reporting, and public health issues. Secondary exploratory findings from the review identified important patterns regarding the prevention paradox, patient decision-making, doctor-patient relationship, and equity.
Conclusions The enthusiasm for precision medicine has led to the rapid implementation of genetic testing for preventative purposes. It is important to understand the harms and benefits of these tests to improve informed patient decision-making.
Currently, there is limited evidence to support how predictive testing can reduce CRC at the population level. Although there appears to be benefit for a selected high-risk group testing for MMR mutations, it is difficult to advocate for PGT with the quality of measures included in this review.
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