Physical Activity for Adults in the Ontario Breast Screening Program

There is "strong" evidence that physical activity (PA) can reduce the risk of breast cancer (Bernstein, 2009; Kehm et al., 2020), which is important for individuals at higher-than-average risk due to their family history or genetic susceptibility. PA can also enhance quality of life (QoL), fitness, and surrogate markers (e.g., weight) linked to cancer prognosis (Ligibel et al., 2019; Patel et al., 2019). Despite this evidence, most adults are insufficiently active, meaning they do not meet Canadian recommendations of at least 150 minutes of PA each week (Statistics Canada, 2020). This study aims to develop materials that can help increase the number of adults at higher-than-average risk who meet PA recommendations, alongside improving QoL and body mass index (BMI; a measure of one's body weight-height ratio). Participants will include individuals assigned female at birth, aged 30-69 years, at high-risk of breast cancer registered in the Ontario Breast Screening Program who will be randomly assigned to receive (1) the intervention, which includes a copy of PA recommendations (Canadian Society for Exercise Physiology \[CSEP\] recommendations for adults plus content spotlighting PA benefits) plus a PA motivation package featuring three online webinars (explaining PA benefits and how to get started), digitized PA materials (providing evidence-based tools to modify behaviour), and a digitized logbook (to track PA) or (2) only a copy of PA recommendations.

Inclusion Criteria: * English- and French-speaking adults enrolled in the Ontario Breast Screening Program; * Aged 30-69 years; * Assigned female sex at birth; * Be at high risk for breast cancer as identified through Category A or B, after genetic assessment: (a) Category A individuals meet ≥1 of the following criteria: (i) known carrier of a gene mutation (e.g., BRCA1, BRCA2), (ii) first degree relative of a carrier of a gene mutation (e.g., BRCA1, BRCA2), received genetic counselling but declined genetic testing, (iii) previously assessed as having ≥25% lifetime risk of breast cancer on basis of family history, or (iv) received chest radiation before age 30 and ≥ 8 years previously. (b) Category B individuals meet ≥1 of the following criteria: (i) first degree relative of a carrier of a gene mutation (e.g., BRCA1, BRCA2), has not had genetic counselling or testing, (ii) a personal or family history of ≥1 of the following: ≥2 cases of breast cancer and/or ovarian cancer in closely related blood relatives, bilateral breast cancer, both breast cancer and ovarian cancer in the same individual, breast cancer at age ≤35 years, invasive serous ovarian cancer, breast cancer and/or ovarian cancer in Ashkenazi Jewish families, an identified gene mutation (e.g., BRCA1, BRCA2) in any blood relative, male breast cancer. Exclusion Criteria: Individuals self-reporting * \>150 minutes of moderate-to-vigorous intensity physical activity in the past week; * no access to an internet connected device; * a condition preventing physical activity (e.g., uncontrolled hypertension)