Association of a healthy lifestyle index with risk of breast cancer among women with normal body mass index in the UK Biobank

A high healthy lifestyle index (HLI), a composite score based on good diet quality, low alcohol consumption, no smoking, moderate to high physical activity, and waist circumference <80cm, has been consistently associated with a reduced risk of breast cancer (BC). Recently, high levels of body fat were found to be associated with an elevated risk of BC in postmenopausal women with a normal body mass index (BMI) (18.5-<25 kg/m2). Whether the HLI is associated with BC risk in women with normal BMI is unknown.
102,572 women aged 40-69 years with a normal BMI at enrolment into the UK Biobank cohort study were studied. The HLI was created by assigning to each component higher scores for healthier behaviors and then summing the scores. The HLI was categorised by tertiles and age- and multivariable-adjusted hazard ratios (HRs) for the association of the HLI with BC risk by menopausal status were estimated.
In postmenopausal women, compared to a low HLI, higher scores were associated with a reduced risk of BC (HRHLI-3rd tertile 0.76; 95% CI, 0.64-0.91). Findings were similar for premenopausal women, although they did not reach statistical significance, except when smoking status was excluded from the HLI score (HLI without smoking: HR3rd tertile, 0.71; 95% CI, 0.56-0.90).
In normal BMI postmenopausal women, a high HLI score was associated with a reduced risk of BC. Following a healthy lifestyle may reduce the risk of BC among normal weight postmenopausal women, the authors conclude.
Source: Association of a healthy lifestyle index with risk of breast cancer among women with normal body mass index in the UK Biobank. Rita Peila, Rhonda S Arthur, Andrew J Dannenberg and Thomas E Rohan. Cancer Epidemiol Biomarkers Prev December 21 2021.