评估由于队列研究基线中已经存在的诊断前体重减轻的潜在偏差，导致超重导致的癌症病例比例（称为群体归因分数（PAF））的潜在低估程度，并尽可能克服它可能。对来自英国生物银行队列参与者的数据进行了分析，年龄为 40-69 岁，之前没有癌症诊断。我们评估了超重与肥胖相关癌症发病率的关联程度，并分别评估了胃肠道 (GI) 癌症和其他癌症的发病率。使用多变量 Cox 比例风险模型，在体重测量后的不同时间段内估计了基线超重的风险比 (HR) 及其 95% 置信区间 (CI) 和 PAF。 在 458,660 名参与者中，20,218 人患有肥胖相关疾病中位 11 年随访期间的癌症，包括 8,460 例胃肠道癌症和 11,765 例非胃肠道癌症。招募后四年以上发生的癌症的 PAF 远高于最初四年内发生的癌症：胃肠道癌、非胃肠道癌和所有肥胖相关癌症的总和分别为 17.7% 和 7.2%、21.4% 和 11.7%。就总癌症（包括与超重没有确定关系的癌症）而言，在 0-4 年和 4-14 年的随访期间，PAF 估计为 5.1% 和 8.8%。 归因于超重的癌症比例体重可能远大于先前根据随访时间短的队列研究估计的体重，或者在分析中没有或仅有限地排除早期随访的情况。© 2024。作者。

To evaluate the magnitude of the potential underestimation of the proportion of cancer cases attributable to excess weight, known as population attributable fraction (PAF), due to potential bias from prediagnostic weight loss already present at baseline of cohort studies and to overcome it as much as possible.Data from the UK Biobank cohort participants aged 40-69 without prior cancer diagnosis were analyzed. We assessed the magnitude of associations of excess weight with the incidence of obesity-related cancers combined, and separately for gastrointestinal (GI) and other cancers. Using multivariable Cox proportional hazards models, hazard ratios (HR) and their 95% confidence intervals (CI), and PAFs for excess weight at baseline were estimated for various periods of time after weight measurements.Of 458,660 participants, 20,218 individuals developed obesity-related cancers during a median 11.0-year follow-up, comprising 8,460 GI, and 11,765 non-GI cancers. PAFs were much higher for cancers occurring more than four years after recruitment than for cancers occurring within the initial four years: 17.7% versus 7.2%, 21.4% versus 11.7% for GI, non-GI and all obesity-related cancers combined, respectively. With respect to total cancer (including cancers with no established relationship with excess weight), PAFs were estimated as 5.1% and 8.8% for the 0-4 and 4-14-year periods of follow-up.The proportion of cancers attributable to excess weight is likely substantially larger than previously estimated based on cohort studies with short follow-up time or no or only limited exclusion of the early years of follow-up from the analyses.© 2024. The Author(s).