Supplementary Material for: Receiving a pathogenic variant in a population breast cancer screening trial: a mixed method study

Introduction: Risk-based breast cancer screening aims to address persistent high morbidity and mortality. This study examines the experience of participants in the WISDOM (Women Informed to Screen Depending on Measures of Risk) trial who received a pathogenic variant in one of nine high or moderate penetrance breast cancer genes.
Methods: Participants completed a brief survey (n=181) immediately following results disclosure and one year later. Descriptive statistics were computed and comparisons between participants at different risk levels were performed using Fisher’s Exact and McNemar’s tests. Analysis of qualitative interviews (n=42) at 2-4 weeks and six months post results disclosure compared responses at the two timepoints, and explained and elaborated on the survey data.
Results: 66.3% of survey respondents felt very or moderately prepared to receive genomic results. At the T1 survey 80.7% of participants had shared the genetic result with a blood relative, increasing to 88.4% at T2; providing information and encouraging cascade testing were the most common reasons for sharing. Communication with a blood relative, other health care providers beyond the primary care provider, and cascade testing were higher for participants with a high risk than low or moderate risk genomic finding. Qualitative interviews elucidated varied reasons why participants felt (un)prepared for the results, including whether or not they had a family history of breast cancer, and illustrate the complexity of decision-making about sharing results.
Conclusions: Although most participants communicated results with family members and health care providers in accord with their risk level, questions remain about how to adequately prepare individuals to receive pathogenic results, ensure timely and accessible follow-up care, and facilitate genetic counseling and cascade testing of at-risk relatives in the setting of population risk-based screening.