The preventable burden of breast cancers for premenopausal and postmenopausal women in Australia: A pooled cohort study

Abstract

Estimates of the future breast cancer burden preventable through modifications to current behaviours are lacking. We assessed the effect of individual and joint behaviour modifications on breast cancer burden for premenopausal and postmenopausal Australian women, and whether effects differed between population subgroups. We linked pooled data from six Australian cohort studies (n = 214,536) to national cancer and death registries, and estimated the strength of the associations between behaviours causally related to cancer incidence and death using adjusted proportional hazards models. We estimated exposure prevalence from representative health surveys. We combined these estimates to calculate Population Attributable Fractions (PAFs) with 95% confidence intervals (CIs), and compared PAFs for population subgroups. During the first 10 years follow‐up, there were 640 incident breast cancers for premenopausal women, 2,632 for postmenopausal women, and 8,761 deaths from any cause. Of future breast cancers for premenopausal women, any regular alcohol consumption explains 12.6% (CI = 4.3–20.2%), current use of oral contraceptives for ≥5 years 7.1% (CI = 0.3–13.5%), and these factors combined 18.8% (CI = 9.1–27.4%). Of future breast cancers for postmenopausal women, overweight or obesity (BMI ≥25 kg/m2) explains 12.8% (CI = 7.8–17.5%), current use of menopausal hormone therapy (MHT) 6.9% (CI = 4.8–8.9%), any regular alcohol consumption 6.6% (CI = 1.5–11.4%), and these factors combined 24.2% (CI = 17.6–30.3%). The MHT‐related postmenopausal breast cancer burden varied by body fatness, alcohol consumption and socio‐economic status, the body fatness‐related postmenopausal breast cancer burden by alcohol consumption and educational attainment, and the alcohol‐related postmenopausal breast cancer burden by breast feeding history. Our results provide evidence to support targeted and population‐level cancer control activities.

A Complex Systems Model of Breast Cancer Etiology: The Paradigm II Conceptual Model

“…There are few other efforts in the literature to describe the complexity of etiologic factors in breast cancer. However, a recent study that pooled six cohort studies from Australia reported on the strength of modifiable behavioral risk factors with a focus on prevention at population levels (162). By using population attributable fractions they identified alcohol as the leading modifiable risk factor for premenopausal women and obesity and alcohol consumption as the most modifiable factors for postmenopausal women.…”

Key steps for effective breast cancer prevention

“…Similar results were found in the Million Women Study 135 . A large prospective pooled Australian cohort, Arriaga et al, 2019 136 have recently shown that regular alcohol consumption is the leading modifiable cause of BC burden for premenopausal women, explaining 12.6% of BCs.…”

“…older premenopausal women with a strong family history of the disease) the increase in absolute risk is likely to be of more importance. In fact, it has been estimated that 7% of BC burden for premenopausal women is owing to the use of hormonal contraceptives for 5 or more years 136 . US statistics indicate that as much as 10% of OCP users are older premenopausal women aged 40-49 286 .…”

Alcohol�s Effects on Breast Cancer in Women

“…For example, in Australia, it has been estimated that any regular consumption of alcohol accounts for 12.6% and 6.6% of premenopausal and postmenopausal breast cancer, respectively. 84 Alcohol consumption accounts for 12% of breast cancer in the United Kingdom. 11 In the United Kingdom, regular consumption of each additional drink per day accounts for 11 additional breast cancers per 1,000 women in their lifetime, up to age 75.…”