Optimizing Risk Communication for Lynch Syndrome: Results of a Randomized Controlled Trial of Visual Arrays for Genetic Testing

Background/Objectives: We aimed to test two different visual arrays for helping individuals accurately interpret colorectal cancer risk in Lynch syndrome. We also sought to examine factors associated with intention to share genetic test results with blood relatives. Methods: Participants were recruited through Amazon Mechanical Turk (July–August 2025). Participants completed an online REDCap survey evaluating genetic literacy/numeracy and risk perception (Tripartite Model of Risk Perception). Participants were randomized to a risk visualization—either a standard icon array or a sequential icon array intended to decrease cognitive load. Subsequently, participants were randomized to a communication choice scenario—a nondirective (choice) frame or an “enhanced choice” with a behavioral nudge based on the Theory of Planned Behavior. Results: Participants’ (n = 1041) estimation of colorectal cancer risk did not differ according to visualization type (icon array: 60.36 ± 15.86%, sequential array: 60.91 ± 15.73%, p = 0.58). Intention to share genetic testing outcomes with family members was not influenced by the behavioral nudge (p = 0.23). Neither risk estimation nor intent to communicate results to blood relatives were affected by individual perceived colorectal cancer risk, health literacy/numeracy, education, previous genetic testing, personal cancer history, or family cancer history (all p > 0.11 and p > 0.21, respectively). Conclusions: This study found that visual array type did not affect estimated cancer risk, and decision frame did not affect intention to share genetic testing results. Findings could inform the development of online approaches to expand decision support for hereditary cancer syndromes (Clinicaltrials.gov #NCT06994832).