本研究旨在通过荟萃分析评估乳腺癌与早期体型间的关系，并提出相应建议。本文纳入了截至2021年4月5日的观察性研究，这些研究探讨了未满18岁的患/无乳腺癌的妇女使用Stunkard体型评分量表/ Sørensen体型评估其18岁之前的体型及其乳腺癌风险。采用随机/固定效应模型，估计汇总的相对风险（RRs）和95％置信区间（CIs）。然后，使用受限制的三次样条分析进行非线性剂量-反应荟萃分析。共有6篇文章涉及341,905名个体中的15,211名乳腺癌患者，用于对早期体型和乳腺癌风险进行荟萃分析。汇总结果显示，体型增加时的保护效果随着体型增加而加强，直到达到6。受限制的三次样条模型表明，体型和乳腺癌之间存在线性关系（P-非线性性=0.533）。根据绝经状态的亚组分析显示，儿童期体型的增加对绝经后乳腺癌具有越来越强的保护作用，从体型3到体型6，乳腺癌风险降低了0.887倍（RR=0.887, 95％ CI：0.842，0.934）至0.759倍（RR=0.759, 95％ CI：0.631，0.913）（P-非线性性=0.880），但在绝经前乳腺癌人群中没有发现这种关联（P-非线性性=0.757）。根据年龄分层，对于10岁以下的人群，体型增加与乳腺癌风险显著降低相关。从体型3到体型6，乳腺癌风险减少了9.7-27.7％（P-非线性性=0.175）。根据早期脂肪堆积情况，我们的数据支持乳腺癌风险与负相关，尤其是在10岁以下和绝经后的妇女中。由于超重的女孩可能继续保持超重甚至发展为肥胖，而成年人的超重和肥胖与乳腺癌及其他癌症和各种慢性疾病的风险增加有关。因此，我们建议儿童在整个生命期间都应保持正常或稍有肥胖的体型。© 2023年。作者（s）独家许可给Springer Nature有限公司。

This study aims to evaluate the relationship between breast cancer and somatotypes during early life by meta-analysis and give the corresponding advice.Observational studies till April 5, 2021, which explore women with/without breast cancer who used the Stunkard Figure Rating Scale/Sørensen Somatotypes to evaluate their somatotype before 18 years of age and distant breast cancer risk were included. Using random/fixed-effect models, the pooled relative risks (RRs) and 95% confidence intervals (CIs) were estimated. Then a nonlinear dose-response meta-analysis was conducted using restricted cubic spline analysis.Six articles involving 15,211 breast cancer patients from 341,905 individuals were included for performing a meta-analysis of early somatotype and breast cancer risk. The pooled results showed that the protection became stronger with the increase of somatotype until it reached 6. The restricted cubic spline model indicated a linear relationship between somatotypes and breast cancer (P-nonlinearity = 0.533). Subgroup analysis of menopausal status showed that increasing somatotype during childhood was increasingly protective against postmenopausal breast cancer from somatotype 3 to somatotype 6, with a 0.887-fold (RR = 0.887, 95% CI: 0.842, 0.934) to 0.759-fold (RR = 0.759, 95% CI: 0.631, 0.913) decreased risk of breast cancer (P-nonlinearity = 0.880), but this association was not found in the population with premenopausal breast cancer (P-nonlinearity = 0.757). When stratified by age, among people younger than 10 years of age, an increase in somatotype was associated with a statistically significant reduction in breast cancer risk. From somatotype 3 to somatotype 6, the risk of breast cancer was reduced by 9.7-27.7% (P-nonlinearity = 0.175).With early-life adiposity, our data support an inverse association with breast cancer risk, especially age less than 10 years and in postmenopausal women. Since girls with overweight likely remain overweight or even develop obesity in adulthood. While adults with overweight and obese are at increased risk of breast cancer and other types of cancer and various chronic diseases. Hence, we recommend that children should maintain a normal or slightly fat somatotype throughout all periods of life.© 2023. The Author(s), under exclusive licence to Springer Nature Limited.