Randomised trial of population‐based BRCA testing in Ashkenazi Jews: long‐term secondary lifestyle behavioural outcomes

OBJECTIVE: Ashkenazi‐Jewish (AJ) population‐based BRCA testing is acceptable, cost‐effective and amplifies primary prevention for breast & ovarian cancer. However, data describing lifestyle impact are lacking. We report long‐term results of population‐based BRCA testing on lifestyle behaviour and cancer risk perception. DESIGN: Two‐arm randomised controlled trials (ISRCTN73338115, GCaPPS): (a) population‐screening (PS); (b) family history (FH)/clinical criteria testing. SETTING: North London AJ‐population. POPULATION/SAMPLE: AJ women/men >18 years. Exclusions: prior BRCA testing or first‐degree relatives of BRCA‐carriers. METHODS: Participants were recruited through self‐referral. All participants received informed pre‐test genetic counselling. The intervention included genetic testing for three AJ BRCA‐mutations: 185delAG(c.68_69delAG), 5382insC(c.5266dupC) and 6174delT(c.5946delT). This was undertaken for all participants in the PS arm and participants fulfilling FH/clinical criteria in the FH arm. Patients filled out customised/validated questionnaires at baseline/1‐year/2‐year/3‐year follow‐ups. Generalised linear‐mixed models adjusted for covariates and appropriate contrast tests were used for between‐group/within‐group analysis of lifestyle and behavioural outcomes along with evaluating factors associated with these outcomes. Outcomes are adjusted for multiple testing (Bonferroni method), with P < 0.0039 considered significant. OUTCOME MEASURES: Lifestyle/behavioural outcomes at baseline/1‐year/2‐year/3‐year follow‐ups. RESULTS: 1034 participants were randomised to PS (n = 530) or FH (n = 504) arms. No significant difference was identified between PS‐ and FH‐based BRCA testing approaches in terms of dietary fruit/vegetable/meat consumption, vitamin intake, alcohol quantity/ frequency, smoking behaviour (frequency/cessation), physical activity/exercise or routine breast mammogram screening behaviour, with outcomes not affected by BRCA test result. Cancer risk perception decreased with time following BRCA testing, with no difference between FH/PS approaches, and the perception of risk was lowest in BRCA‐negative participants. Men consumed fewer fruits/vegetables/vitamins and more meat/alcohol than women (P < 0.001). CONCLUSION: Population‐based and FH‐based AJ BRCA testing have similar long‐term lifestyle impacts on smoking, alcohol, dietary fruit/vegetable/meat/vitamin, exercise, breast screening participation and reduced cancer risk perception.