Breast cancer survivors with pain: an examination of the relationships between body mass index, physical activity, and symptom burden

Purpose: Overweight and obesity are common for breast cancer survivors and associated with high symptom burden (i.e., pain, fatigue, depressive symptoms). Physical activity may protect breast cancer survivors with higher body mass indexes (BMI) from increased symptoms. However, the role of physical activity in buffering the relationship between higher BMI and greater symptoms is unclear.

Methods: Baseline data from a randomized trial investigating Pain Coping Skills Training among breast cancer survivors (N = 327) with pain were used to examine the relationship between self-reported BMI (kg/m²) and physical activity level (Rapid Assessment of Physical Activity; suboptimal vs. optimal) with pain (Brief Pain Inventory; severity and interference), fatigue (PROMIS-Fatigue short form), and depressive symptoms (Center for Epidemiological Studies Depression Scale). Analyses were conducted in SPSS. Hayes PROCESS macro (Model 1) assessed whether physical activity moderated the relationship between BMI and symptoms.

Results: Lower BMI (B = .06, p < .01) and optimal physical activity (B = - .69, p < .01) were independently associated with lower pain interference. Lower BMI was also associated with lower pain severity (B = .04, p < .001). Neither BMI nor physical activity was associated with fatigue or depressive symptoms. Physical activity did not moderate the relationship between BMI and symptoms.

Conclusions: Among breast cancer survivors experiencing pain, higher BMI and being less physically active were related to greater pain (i.e., severity and/or interference). Physical activity did not buffer the relationships between BMI and pain, fatigue, and depressive symptoms, suggesting that physical activity alone may not be sufficient to influence the strength of the relationships between BMI and symptoms.