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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. What's new? While several potentially‐modifiable behavioural risk factors have been identified for breast cancer, estimates of the preventable future breast cancer burden are still lacking. Based on a large prospective pooled Australian cohort, here the authors reveal that regular alcohol consumption is the leading modifiable cause of breast cancer burden for premenopausal women (12.6%). Using the latest exposure prevalence information, the authors rank body fatness as the leading cause of preventable breast cancer burden for postmenopausal women (12.8%), with regular alcohol consumption also contributing substantially (6.6%). The findings provide evidence to support targeted and population‐level cancer control activities in Australia and beyond. [ABSTRACT FROM AUTHOR]

Evidence on the endometrial and ovarian cancer burden preventable through modifications to current causal behavioural and hormonal exposures is limited. Whether the burden differs by population subgroup is unknown. We linked pooled data from six Australian cohort studies to national cancer and death registries, and quantified exposure-cancer associations using adjusted proportional hazards models. We estimated exposure prevalence from representative health surveys. We then calculated Population Attributable Fractions (PAFs) with 95% confidence intervals (CIs), accounting for competing risk of death, and compared PAFs for population subgroups. During a median 4.9 years follow-up, 510 incident endometrial and 303 ovarian cancers were diagnosed. Overweight and obesity explained 41.9% (95% CI 32.3–50.1) of the endometrial cancer burden and obesity alone 34.5% (95% CI 27.5–40.9). This translates to 12,800 and 10,500 endometrial cancers in Australia in the next 10 years, respectively. The body fatness-related endometrial cancer burden was highest (49–87%) among women with diabetes, living remotely, of older age, lower socio-economic status or educational attainment and born in Australia. Never use of oral contraceptives (OCs) explained 8.1% (95% CI 1.8–14.1) or 2500 endometrial cancers. A higher BMI and current long-term MHT use increased, and long-term OC use decreased, the risk of ovarian cancer, but the burden attributable to overweight, obesity or exogenous hormonal factors was not statistically significant. Excess body fatness, a trait that is of high and increasing prevalence globally, is responsible for a large proportion of the endometrial cancer burden, indicating the need for effective strategies to reduce adiposity. • Contemporary estimates of endometrial cancer burden attributable to body fatness. • Overweight and obesity explain 42%, and obesity alone explains 35% of endometrial cancers. • First estimates of future endometrial cancer burden for population subgroups. • Overweight and obesity explain 49–87% of the endometrial cancer burden for some subgroups of women. [ABSTRACT FROM AUTHOR]

Background Estimates of the future burden of invasive cancer attributable to current modifiable causal exposures can guide cancer prevention. Methods We linked pooled data from seven Australian cohort studies (N = 367,058) to national cancer and death registries, and estimated exposure-cancer and exposure-death associations using adjusted proportional hazards models. We estimated exposure prevalence from contemporary national health surveys and calculated population attributable fractions (PAFs) and 95% confidence intervals, using advanced methods accounting for competing risk of death. Results Current levels of past and current smoking explain 36.1% (95%CI 33.2%-38.9%), body fatness 13.6% (10.9%-16.2%) and alcohol consumption exceeding two drinks/day 2.3% (1.0%-3.6%) of cancers causally related to these exposures, corresponding to 210,000, 81,300 and 14,800 cancers in Australia in the next 10 years, respectively. Ever smoking is the leading modifiable cause of lung (82.1%), bladder (49.8%), oesophageal (42.8%), liver (39.8%), head and neck (35.6%), and pancreatic (21.3%) cancer burden. Body fatness is the leading modifiable cause of corpus uteri (42.5%), gastric cardia (33.6%), renal cell (29.1%), thyroid (20.1%), colorectal (12.6%) and postmenopausal breast (12.6%) cancer burden. The absolute numbers of cancers in the next 10 years attributable to smoking are highest for lung cancer (114,000). The numbers of cancers attributable to body fatness and alcohol are highest for colorectal cancer (23,000 and 9,900, respectively). Conclusions More reliable advanced methods demonstrate large proportions and numbers of cancers are preventable by modifying behaviours. Key messages Ever smoking and body fatness are the leading causes of preventable future burden of causally related cancers in Australia. [ABSTRACT FROM AUTHOR]