The future burden of head and neck cancers attributable to modifiable behaviours in Australia: a pooled cohort study.

BACKGROUND Estimates of future burden of cancer attributable to current modifiable causal exposures can guide cancer prevention. We quantified future head and neck cancer burden in Australia attributable to individual and joint causal exposures, and assessed whether these burdens differ between population subgroups. METHODS We estimated the strength of the associations between exposures and head and neck cancer using adjusted proportional hazards models from pooled data from seven Australian cohorts (N=367,058) linked to national cancer and death registries and estimated exposure prevalence from the 2017-2018 Australian National Health Survey. We calculated Population Attributable Fractions (PAFs) with 95% confidence intervals (CIs), accounting for competing risk of death, and compared PAFs for population subgroups. RESULTS Contemporary levels of current and former smoking contribute 30.6% (CI=22.7-37.8%), alcohol consumption exceeding two standard drinks per day 12.9% (CI=7.6-17.9%), and these exposures jointly 38.5% (CI=31.1-45.0%) to the future head and neck cancer burden. Alcohol-attributable burden is triple and smoking-attributable burden is double for men compared with women. Smoking-attributable burden is also at least double for those consuming more than two alcoholic drinks daily or doing less than 150 minutes of moderate or 75 minutes of vigorous activity weekly, and for those aged under 65 years, unmarried, with low or intermediate educational attainment or lower socio-economic status, compared with their counterparts. CONCLUSIONS Two-fifths of head and neck cancers in Australia are preventable by investment in tobacco and alcohol control. IMPACT Targeting men and other identified high-burden subgroups can help to reduce head and neck cancer burden disparities.