在这项研究中，我们旨在计算2020年伊朗可改变风险因素引起的癌症比例。使用三个数据来源计算了已知癌症风险因素的人群可归因分数（PAFs）：国家癌症发病报告、从全球和国家的meta分析中提取的相对风险，以及来自国家/地区人群调查的暴露流行率。除了总体癌症外，PAFs分别在男性和女性中为每个癌症部位估计。总的来说，2020年伊朗32.6%的癌症是由已知风险因素引起的。男性（40.2%）的PAF是女性（21.1%）的两倍。吸烟（15.4%）、超重（5.0%）、吸食鸦片（3.9%）和H. pylori感染（3.8%）是癌症的主要原因。对于男性，最高PAFs为吸烟（26.3%）、吸食鸦片（6.8%）和超重（3.1%），而对于女性，最高PAFs为超重（7.2%）、H. pylori感染（2.7%）和吸烟（2.7%）。在伊朗男性和女性中，水烟吸烟的PAFs分别为2%和0.9%。伊朗的三分之一的癌症发生是由可改变的暴露引起的，主要是吸烟、超重和H. pylori感染。在伊朗，鸦片使用和水烟吸烟共占男性癌症发生的8.8%，女性为1.3%。这些新兴风险因素应在未来的PAF研究中加以考虑。© 2023 UICC.

In the current study, we aimed to calculate the fraction of cancer attributable to modifiable risk factors in Iran in 2020. Population attributable fractions (PAFs) were calculated for established cancer risk factors using three data sources: the national cancer incidence reports, relative risks extracted from global and national meta-analyses, and exposure prevalence from national/subnational population-based surveys. In addition to overall cancers, the PAFs were estimated separately for each cancer site among men and women. Overall, 32.6% of cancers in 2020 in Iran were attributable to known risk factors. The PAF in men (40.2%) was twice as high as in women (21.1%). Cigarette smoking (15.4%), being overweight (5.0%), opium use (3.9%) and H. pylori infection (3.8%) were the leading causes of cancers. For men, the highest PAFs belonged to cigarette smoking (26.3%), opium use (6.8%) and being overweight (3.1%), while for women, the highest PAFs belonged to being overweight (7.2%), H. pylori infection (2.7%) and cigarette smoking (2.7%). Among Iranian men and women, the PAFs of waterpipe smoking were 2% and 0.9%, respectively. A third of incident cancers in Iran are due to modifiable exposures, mainly cigarette smoking, being overweight, and H. pylori infection. Opium consumption and waterpipe smoking collectively accounted for 8.8% of cancer occurrence in men and 1.3% in women in Iran. These emerging risk factors should be taken into consideration in future PAF studies.© 2023 UICC.