Aims
To quantify Australia's preventable kidney cancer burden via the first international Population Attributable Fraction (PAF) meta-analysis. Prior Australian analyses lacked statistical power for female-specific estimates. We pooled estimates from Australian cohorts and the UK Biobank to achieve robust sex-specific results.
Methods
We estimated sex-specific associations of BMI and smoking history with incident kidney cancer using adjusted parametric survival models within four cohorts: the 45 and Up Study (N=267,029), Melbourne Collaborative Cohort Study (N=41,514), Australian Longitudinal Study on Women's Health (N=38,487), and UK Biobank (N=502,131). Linkage to national registries identified 1,623 incident kidney cancers and 31,705 deaths over 10-year follow-up. Cohort-specific hazard ratios (HRs) were combined with 2022 Australian National Health Survey exposure prevalences to calculate PAFs and 95% confidence intervals (CIs) accounting for competing mortality. Cohort-specific HRs and PAFs were meta-analysed using an inverse-variance weighted random-effects model.
Results
Obesity was the strongest predictor of kidney cancer in women (HR=2.11; 95% CI: 1.71, 2.60) and current smoking in men (HR=1.89; 1.55, 2.31). However, due to higher exposure, obesity was the leading preventable cause of kidney cancer, explaining 24.2% (17.3%, 30.6%) of cases in women and 18.3% (9.0%, 26.7%) in men. Ever smoking explained 14.4% (8.5%, 20.0%) in men and 11.8% (5.0%, 18.0%) in women, with current smoking responsible for 8.8% (5.4%, 12.1%) and 4.4% (-4.2%, 12.4%), respectively. Overweight contributed 10.9% (5.7%, 15.7%) in men and 6.2% (-1.3%, 13.2%) in women. Jointly, body fatness and ever smoking explained 41.5% (32.5%, 49.3%) of cases in men and 38.7% (28.4%, 47.5%) in women, with body fatness and current smoking explaining 37.4% (28.3%, 45.3%) and 35.3% (25.2%, 44.1%), respectively.
Conclusions
The overall preventable kidney cancer burden is similar between sexes, with obesity the leading modifiable cause in both women and men. This emphasises the urgent need to prioritise obesity prevention in public health policy.