Title: The impact of physical activity on physical and mental health among breast cancer survivors over time.
Principal Investigator: Catherine Sabiston, PhD. (McGill University)
Co-investigators: Jennifer O’Loughlin, Ph.D. (CHUM, Université de Montréal), Carsten Wrosch, Ph.D. (Concordia University)

According to the Canadian Cancer Society, one in nine women will be diagnosed with breast cancer during her lifetime, and upwards of 85% of these women will survive the disease. Relative to same-aged women without cancer, breast cancer survivors are at increased risk for other chronic illnesses including cardiovascular disease, diabetes, osteoporosis, physical function declines, and depression. The increased risk for comorbid chronic illnesses may stem from genetic predisposition and/or the cancer treatments endured, but also from lifestyle-related factors including age, low levels of physical activity, and overweight status. Nearly 50% of Canadian breast cancer survivors are overweight or obese, and sedentarism is more prevalent for these women compared to healthy-weight survivors.

Appropriate participation in physical activity is beneficial for both physical and emotional health, and there is evidence that breast cancer survivors who participate in regular vigorous exercise have improved their strength, aerobic fitness and body composition. In addition, regular exercise is associated with improved sleep, improved cardiovascular risk profiles, and enhanced subjective well-being through experiences of psychological growth and decreases in emotional distress. Despite the known health benefits of exercise, few breast cancer survivors incorporate exercise routinely into their lives - with over 55% of these women classified as inactive.

Lifestyle physical activity is a strategy to help sedentary individuals adopt more active lifestyles. This paradigm encourages the daily accumulation of at least 30 minutes of self-selected activities, either planned or unplanned, including all leisure, occupational, and household tasks that are at least moderate in intensity. Based on our own work, lifestyle physical activity is a gateway to traditional exercise among sedentary, overweight women. However, the longitudinal impact of lifestyle physical activity on subjective wellbeing, biological functioning, and physical health among overweight breast cancer survivors has not yet been investigated.

Therefore, this study aims to examine the influence of lifestyle physical activity on subjective wellbeing, biological functioning and physical health outcomes over time among breast cancer survivors. In addition, we will investigate psychological factors that are likely related to lifestyle physical activity behaviour. In aging populations, individuals who are motivated to address their health threats, and who are capable of disengaging from unattainable goals and reengaging in new goals, have more adaptive physical and emotional health outcomes. We hypothesize that breast cancer survivors with these characteristics are more likely to engage in lifestyle physical activity. The current study therefore also seeks to identify the psychological factors that may be involved in the process of adopting lifestyle physical activity.

To address these objectives, we will collect self-report and objective data from 200 women who have been treated for breast cancer and who have undergone chemotherapy on self-regulatory strategies (control of health threats, goal disengagement), lifestyle physical activity (pedometers, accelerometers, self-report), subjective wellbeing (psychological growth, emotional distress), biological functioning (cortisol, c-reactive protein), and physical health problems at six times during the first 18 months following treatment for breast cancer. The results of this study may provide longitudinal evidence that lifestyle physical activity is an antecedent to physical and emotional health among overweight breast cancer survivors. This study is a first step towards better understanding active living in a vulnerable group of women, and the findings will help shape health promotion efforts and policy focused on effective strategies for early breast cancer survivorship.