The IMproving Access to Genetic INformation for Everyone (IMAGINE) Study: A Prospective Trial of a Mainstreaming Model for Hereditary Cancer Multigene Panel Testing Among Cancer Patients - Efficient yet effective models for delivering genetic counseling and testing are sorely needed to meet increasing demands for timely genetic risk information. Traditional germline genetic testing models, which include in-depth genetic counseling both before and after testing, are time intensive and place substantial demands on the limited genetic counselor workforce. A “mainstreaming” model, which allows for non-genetics healthcare providers to order genetic testing without pre-test genetic counseling, with support from genetic counselors at the time of result disclosure, has shown promise. Yet, past evaluations of mainstreaming models have been hampered by serious limitations: Studies were restricted to the context of BRCA1/2 testing and do not reflect the growing use of multigene panel testing (MGPT); rarely used rigorous experimental study designs or evaluated theoretically-relevant decision-making, psychosocial, and communication outcomes; have not capitalized on opportunities to improve post-test clinical and familial communication; and neither included nor addressed informational needs of different kinds of patients. We overcome these limitations with the proposed study, the objective of which is to develop, test, and evaluate a mainstreaming model for hereditary cancer MGPT among cancer patients of many different groups. We will first use formative research methods, including transcreation and cognitive interviewing, to adapt existing pre-test educational materials and post-test clinical communication materials for use among the many different types of patients treated at our local hospital partnering sites. Next, we will conduct a randomized controlled trial (RCT) involving patients diagnosed with breast, colorectal, ovarian, pancreatic, or prostate cancer (N=350). Patients will be randomized to obtain access to cancer MGPT through either: i) standard-of-care wherein in-depth pre-test and post-test genetic counseling are provided via telegenetics (i.e., videoconferencing delivered at the site clinic) with standard post-test clinical communication materials, or ii) mainstreaming intervention wherein patients receive the adapted pre-test educational materials with testing ordered by their oncologist, followed by post-test genetic counseling provided via telegenetics with adapted clinical communication materials. Patients will complete assessments of decision-making, psychosocial, and behavioral outcomes at baseline, upon deciding whether to have MGPT, and at 1-week and 6-months following receipt of their test results. This research has the potential to transform genetic counseling and testing practice by ensuring effective risk communication, decision making, and uptake of genomic medicine to by all the groups of patients with hereditary cancer syndromes.