Pre-Diagnosis Diet and Physical Activity and Risk of Cardiovascular Disease Mortality among Female Cancer Survivors

SIMPLE SUMMARY: The number of cancer survivors is increasing; however, cancer survivors are at an increased risk of cardiovascular diseases (CVD) and CVD mortality. Therefore, it is pertinent to understand how lifestyle choices such as dietary patterns and physical activity are associated with this risk. Little is known about the relationship of pre-cancer diagnosis diet quality and physical activity (PA) with CVD among cancer survivors. Most studies have focused on post-cancer diagnosis risk factors, without accounting for their status in the pre-diagnosis period or interaction on CVD mortality. We examined pre-cancer diagnosis diet quality and physical activity in relation with CVD mortality risk in female cancer survivors from the California Teachers Study cohort. We hypothesized that higher diet quality scores and higher physical activity levels prior to cancer diagnosis would be associated with lower risk of CVD mortality in female cancer survivors. ABSTRACT: Sub-optimal diet and physical activity (PA) levels have been associated with increased risk of cardiovascular disease (CVD) mortality. The relationship between pre-cancer diagnosis diet quality and PA level on CVD mortality risk in cancer survivors is unclear. We examined the association between pre-cancer diagnosis diet quality and leisure-time PA and their interaction on CVD mortality in cancer survivors. Diet quality was characterized by the Alternative Mediterranean Diet Index (aMED). Leisure-time PA was converted to a metabolic equivalent of task hours per week (MET-h/wk). During a median of 6.3 years of follow-up of 18,533 female cancer survivors, we identified 915 CVD deaths. aMED score was not associated with CVD mortality. PA level was inversely associated with CVD mortality (HR(Q1-Q4) = 0.74; 95% CI: 0.61–0.88; P(trend) = 0.0014). Compared to cancer survivors with the lowest pre-diagnosis aMED score and PA level, cancer survivors with higher aMED scores and higher MET-hrs/wk were at a 33% lower risk of CVD mortality (HR = 0.67; 95% CI: 0.52–0.87). Overall, this study shows PA to be a strong predictor of CVD mortality in female cancer survivors. Our observations support the importance of PA throughout the lifecycle in lowering CVD mortality risk.