Association between body mass index and breast cancer risk: evidence based on a dose–response meta-analysis

Abstract

Introduction

Breast cancer is the most common cancer in women worldwide. The association between body mass index (BMI) and breast cancer risk has been paid more attention in the past few years, but the findings are still controversial. To obtain a more reliable conclusion, we performed a dose–response meta-analysis on 12 prospective cohort studies comprising 22,728,674 participants.

Methods

Linear and nonlinear trend analyses were conducted to explore the dose–response relationship between BMI and breast cancer risk. The summary relative risk (SRR) and 95% confidence intervals (CIs) were used to evaluate the cancer risk.

Results

The overall results showed a weak positive association between a 5-unit increase in BMI and breast cancer risk, indicating that a 5 kg/m² increase in BMI corresponded to a 2% increase in breast cancer risk (SRR: 1.02, 95% CI: 1.01–1.04, p<0.001). Notably, further subgroup meta-analysis found that higher BMI could be a protective factor of breast cancer risk for premenopausal women (SRR: 0.98, 95% CI: 0.96–0.99, p<0.001). In addition, the dose–response result demonstrated that there was a linear association between BMI and breast cancer risk (P_nonlinearity=0.754).

Conclusion

In summary, this dose–response meta-analysis of prospective cohort studies showed that every 5 kg/m² increase in BMI corresponded to a 2% increase in breast cancer risk in women. However, higher BMI could be a protective factor in breast cancer risk for premenopausal women. Further studies are necessary to verify these findings and elucidate the pathogenic mechanisms.

Keywords:

• BMI
• breast
• dose–response
• cancer
• menopausal

Acknowledgments

The authors thank Yi Zheng, Shanli Li, Yujiao Deng, and Linghui Zhou for their contribution. This work was supported by the National Natural Science Foundation of China (No. 81471670/81274136), the China Postdoctoral Science Foundation funded Projects (No. 2014M560791/2015T81037) and the Key research and development plan, Shaanxi Province, People’s Republic of China (2017ZDXM-SF-066).

Disclosure

The authors report no conflicts of interest in this work.