Sleep traits and breast cancer risk: a two-sample Mendelian randomization study

Area of Science:

• Genetics and Epidemiology
• Cancer Research
• Sleep Science

Background:

• Breast cancer is a leading cause of cancer incidence and mortality in females globally.
• Sleep patterns are increasingly recognized for their significant influence on tumor development and progression.
• Understanding genetic predispositions related to sleep can offer insights into breast cancer risk.

Purpose of the Study:

• To investigate the association between various sleep patterns and overall and subtype-specific breast cancer risk.
• To utilize a two-sample Mendelian randomization (MR) approach to assess causal relationships.
• To identify specific sleep-related traits that may influence breast cancer susceptibility.

Main Methods:

• Employed a two-sample Mendelian randomization (MR) approach.
• Utilized genetic data from UK Biobank and 23andMe for seven sleep patterns (chronotype, sleep duration, daytime napping, etc.).
• Analyzed genome-wide association studies (GWAS) data from the Breast Cancer Association Consortium (BCAC) for cases and controls.

Main Results:

• Chronotype (both morning and evening types) was identified as a contributing factor to overall breast cancer risk.
• Daytime dozing and being a morning person (chronotype) were associated with a reduced risk of general breast cancer.
• Specific associations were found for subtypes: morning chronotype with luminal B and HER2-negative-like breast cancer, and daytime dozing with luminal A-like, luminal B-like, and HER2-enriched-like breast cancer.

Conclusions:

• Chronotype is confirmed as a risk factor for breast cancer, supporting previous observational studies.
• Being a morning person and engaging in daytime dozing may be protective factors against breast cancer.
• Sleep patterns, particularly chronotype and daytime sleep habits, are significant in developing breast cancer prevention strategies.