Psychological, social, and ethical implications of population-based genetic testing among adults: a systematic scoping review protocol with a focus on cancer

The standard clinical genetic testing model for hereditary cancers applies stringent eligibility criteria and consistently misses large numbers of at-risk cancer-susceptibility-gene (CSG) carriers in the general population, leading to missed opportunities for cancer screening/prevention. Advances in technology and understanding of genetics make it possible to expand such testing beyond clinical settings, across different countries and various healthcare settings. Population-based genetic testing (PBGT), which involves offering genetic testing to a broad, unselected population, is a promising strategy for identifying high-risk yet unaffected individuals, helping to maximise prevention and early detection. Successful large-scale implementation of PBGT requires it to be psychologically acceptable, socially responsible, and ethically sound. This review will examine the evidence on psychological, social, and ethical aspects explored in PBGT studies, assess the quality of evidence, and highlight gaps to inform the future design and implementation of PBGT programmes. A systematic scoping review will be conducted across three databases (PubMed, Embase, PsycINFO). Studies are eligible if they: (1) are peer-reviewed; (2) are published between 1994 and 2025; (3) are written in English; (4) recruit otherwise healthy adults (≥18 years); (5) offer predictive germline genetic testing for CSGs, or hypothetical genetic testing and are inferred as population-based; and (6) assess psychological, social, and/or ethical implications. Four reviewers will undertake study screening, data extraction, and evidence synthesis. Data will be extracted from included full-text articles by two independent reviewers. Study quality will be evaluated using the Mixed Methods Appraisal Tool. This systematic scoping review synthesises empirical evidence on the psychological, social, and ethical implications of PBGT. Protocol publication increases transparency and minimises biases such as the selective reporting of outcomes, enhancing the reliability of our findings. The review findings will provide an initial evidence base within the broader assessment of PBGT, highlighting additional evidence needed to inform future research, policy, and practice to support the responsible implementation of PBGT programmes. The Open Science Framework registration number: osf.io/zwjxg.