Dose response relationship between breast cancer and somatotypes during childhood: a systematic review and...

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.