Estimation of population attributable fractions based on integrated global cancer incidence data, 1990-2021.

10536 Background: The global cancer burden is increasing, yet emerging risk factors for cancer incidence have not been comprehensively summarized in terms of the population attributable fraction (PAF) from a global perspective. Methods: We first searched and screened cancer risk factors from 435,977 studies in the Embase, PubMed, and Cochrane databases. Cancer risk effect sizes, such as RR (relative risk), HR (hazard ratio), and IRR (incidence rate ratio) values, were then obtained from meta-analyses. We further estimated population attributable fractions (PAFs) for each risk factor, cancer type, gender, SDI (Socio-demographic Index), modifiability, and trends from 1990 to 2021, using 94 pre-defined risk factors and 39 cancer types. These risk factors include lifestyle factors, environmental exposures, occupational risks, metabolic factors, comorbidities, and family or cancer history. Results: A total of 811 cancer risk effect sizes were obtained covering 75 countries or regions, including 18,084 cancer RR/HR/IRR values. In 2021, 64.1% (56.7% - 71.4%) of global cancer incidences were attributable to the evaluated risk factors, with modifiable risk factors accounting for 57.6%. Among the evaluated cancers, the proportion of incidence cases attributed to risk factors exceeded 50% in 26 types of cancer, with the leading cancers being cervical cancer (97.1%), Kaposi's sarcoma (91.2%), vaginal cancer (87.0%), lung cancer (84.6%), and laryngeal cancer (83.2%). In terms of individual risk factors, tobacco use (17.9%), infection (16.1%), and overweight or obesity (10.2%) contributed the highest PAFs, followed by family and genetic history (6.9%), alcohol consumption (5.7%), cardiovascular diseases (5.0%). The high SDI region shows a higher PAF (68.2% [61.5%–75.0%]) compared to the non-high SDI region (59.6% [52.2%–67.0%]). From 1990 to 2021, the global cancer incidences attributable to risk factors increased from 61.8% to 64.1%. Overweight or obesity, neurological and psychological disorders, and dietary factors were the top three leading increasing risk factors. Conclusions: The global cancer burden is significantly influenced by a wide range of modifiable and non-modifiable risk factors, with over 64% of cancer incidence in 2021 attributable to these factors. The rising trends in overweight or obesity, neurological and psychological disorders, and diabetes factors between 1990 and 2021 highlight the urgent need for targeted interventions to address these rapidly growing risks and reduction of the cancer burden.