JMIR Publications

ABSTRACT

Background:

Anthracycline-based chemotherapy has been mainstay of adjuvant breast cancer therapy for decades. Although effective, anthracyclines place long-term breast cancer survivors at risk of late effects, such as reduced cardiorespiratory fitness and increased risk of cardiovascular disease. Previous research has shown beneficial effects of exercise training on cardiorespiratory fitness, but the effects of exercise on limiting factors for cardiorespiratory fitness, cardiovascular risk factors and patient reported outcomes in long-term survivors are less clear. Whether previous exposure to breast cancer therapy modulates the effects of exercise is also unknown.

Objective:

The primary aim of the CAUSE-trial is to examine the effect of aerobic exercise on cardiorespiratory fitness in anthracycline-treated long-term breast cancer survivors. Secondary aims are to examine effects of exercise training on limiting factors for cardiorespiratory fitness, cardiovascular risk factors and patient reported outcomes, and to compare baseline values and effects of exercise training between similar-aged women with and without prior breast cancer. A third aim is to examine the 24 months post-intervention effects of aerobic exercise on primary and secondary outcomes.

Methods:

The CAUSE-trial is a two-armed randomized controlled trial, where 140 long-term breast cancer survivors, 8-12 years post diagnosis, are assigned to a five-month, non-linear aerobic exercise program with three weekly sessions or to standard care. Seventy similar-aged women with no history of cancer will undergo the same exercise program. Cardiorespiratory fitness measured as peak oxygen consumption (V̇O2peak), limiting factors of V̇O2peak (e.g., cardiac function, pulmonary function, hemoglobin mass, blood volume and skeletal muscle characteristics), cardiovascular risk factors (e.g., hypertension, diabetes, dyslipidemia, obesity, physical activity level and smoking status) and patient reported outcomes (e.g., body image, fatigue, mental health, health-related quality of life) will be assessed at baseline, post-intervention and 24 months post-intervention.

Results:

A total of 209 patients were included from October 2020 to August 2022. The intervention is still ongoing.

Conclusions:

The findings from the CAUSE-trial will provide novel scientific understanding of the potential benefits of exercise training in long-term breast cancers survivors. Clinical Trial: The study was preregistered on clinicaltrials.gov in March 2020 with registration number: NCT04307407.