The Breast Cancer & Physical Activity Level (BC-PAL) Pilot Study

Detailed Description

Rationale and Significance:

Breast cancer is the most common cancer among Canadian women. Physical activity has emerged as a potential lifestyle factor for improving rehabilitation and survival after breast cancer. The American Cancer Society recommends that cancer survivors engage in at least 150 minutes of moderate-vigorous intensity physical activity per week. However, only ≈ 15% of breast cancer survivors reported meeting these physical activity guidelines. Therefore, interventions that promote physical activity behavior change in an unsupervised/home-based setting are needed to provide the necessary tools and support for breast cancer survivors. No study to date has assessed the effects of a lighter intensity physical activity intervention, compared to no additional physical activity prescription (control) or a higher intensity physical activity intervention (comparable to current exercise guidelines), in inactive breast cancer survivors, in addition to the longer-term maintenance effects of these interventions.

Study Aims:

Aim 1: To evaluate the effects of prescribing an additional 300 minutes/week of lighter intensity physical activity (LIPA) or 150 minutes/week of higher intensity physical activity (HIPA) versus no physical activity intervention (control) on total physical activity and sedentary time in inactive breast cancer survivors.

Aim 2: To evaluate the effects of prescribing an additional 300 minutes/week of LIPA or 150 minutes/week of HIPA versus control on markers of health-related fitness (anthropometric measures, body composition, cardio-respiratory fitness) and patient reported outcomes (quality of life, sleep quality, feelings of happiness, perceived feelings of depression) in inactive breast cancer survivors.

Aim 3: To evaluate the longer-term (24-week) maintenance effect of prescribing an additional 300 minutes/week of LIPA or 150 minutes/week of HIPA versus control on our primary and secondary outcomes.

Research Plan:

A three-armed, 12-week pilot randomized controlled trial followed by a 12-week follow-up measurement is proposed. All eligible and interested women are invited to contact and meet with study staff at the Holy Cross Center in Calgary, at which time the study protocol is explained, informed consent obtained and baseline questionnaires distributed. These questionnaires assess: demographic characteristics, sleep quality, perceived health-related quality of life, feelings of happiness and perceived feelings of depression. At the end of this first meeting, participants are asked to wear an Actigraph GTX3® accelerometer for seven days to assess baseline physical activity levels. During a second meeting at the Holy Cross Center, accelerometers are returned to study staff, anthropometric data (height, weight, waist and hip circumferences and body composition) are collected and a maximal treadmill test (modified Balke protocol) is conducted. Participants are then randomized, using a 1:1:1 allocation, into either the control (no intervention), lighter intensity or the higher intensity physical activity interventions. The control group is instructed to maintain baseline physical activity participation. The lighter intensity physical activity (LIPA) group is instructed to accumulate 300 minutes/week of physical activity at an intensity of 40-60% of heart rate reserve. The higher intensity physical activity (HIPA) group is instructed to accumulate 150 minutes of physical activity at an intensity of 60-80% of heart rate reserve. Participants randomized to the LIPA and HIPA groups are given: 1) instructions on physical activity safety and goal setting, proper heart rate monitoring and stretching techniques that should be completed before and after physical activity participation; 2) a publicly-available physical activity guidebook for breast cancer survivors; 3) a Polar A360® device to track heart rate and physical activity time throughout the intervention. Data collected by this device are uploaded to the Polar Flow® application by syncing with a smart phone or a computer with a provided USB cord. Participants are asked to upload their data at least once per week. If a participant does not own a computer or a smart phone, or prefers that the study staff upload these data for them, in-person meetings are arranged to do so. Participants in the LIPA and HIPA groups are also asked to rate the feasibility of achieving the prescribed physical activity targets and record strategies used and barriers encountered during the intervention in a diary. In-person/telephone meetings with these participants occur every three weeks to review data from the Polar A360® device and diary, to reinforce progress/good adherence and discuss/solve any problems or barriers to achieving the prescribed physical activity goals. During weeks 12 (final intervention week) and 24 (final week of the follow-up period), all participants wear an Actigraph GTX3® accelerometer to assess physical activity volume. At the end of weeks 12 (end of the intervention) and 24 (end of the follow-up period), all participants repeat baseline measurements and questionnaires, except for items on demographic characteristics.

The investigators will use intention-to-treat statistical analysis on all participants with follow-up data regardless of adherence to the interventions. An analysis of covariance (ANCOVA) will be used to compare between-group differences in study outcomes at 12- and 24-weeks, compared to baseline, after adjusting for baseline outcomes values.

This pilot randomized controlled trial will provide data on the feasibility of prescribing different physical activity intensities within a home-based setting to increase total physical activity time, reduce sedentary time and improve health outcomes in breast cancer survivors. The investigators will use these data to help design and conceptualize a larger-scale randomized controlled trial.