Physical Activity and Grip Strength as Predictors of Mortality in Breast Cancer Survivors

Abstract

Breast cancer is the leading cause of cancer mortality among women. Clinical factors, such as stage, lymph node involvement, and treatment adherence are known to influence survival; however, less is known about the effects of lifestyle factors at diagnosis, such as physical activity (PA) and grip strength (GS). Purpose: To determine the effects of PA and GS at diagnosis on all-cause mortality in women with breast cancer. Methods: As part of the Strength and Range of Motion cohort, PA exposure and GS were assessed using the Godin Leisure-Time Exercise Questionnaire (GLTEQ) and handgrip dynamometer, respectively. Cox proportional hazards models were used to estimate the hazard ratio (HR) for associations between PA exposure or GS at diagnosis and all-cause mortality, adjusting for influential covariates. Results: At diagnosis, women (n=398) were, on average, 57.1±11.9 years old and overweight (M BMI=29.2± 6.2 kg/m2) with early-stage breast cancer and low levels of PA (M GLETQ=9.2±15.6) and GS (M =49.9±11.5 kg). Across a median follow-up of 151 months, 73 deaths were recorded. The unadjusted and adjusted PA Cox models produced HRs (95% CI) of 0.44 (0.18-1.10, p=.08) and 0.37 (0.13-1.10, p=0.73) (95% CI) and for GS, 0.69 (0.42-1.14, p=0.14) and 0.89 (0.52-1.52, p=0.66), respectively. Conclusions: While the results in these models were not significant, HR directionality indicates there may be protective effects of PA, but more research is needed to investigate trends with a larger sample.