Global breast cancer seasonality

Area of Science:

• Oncology
• Epidemiology
• Chronobiology

Background:

• Human breast cancer incidence exhibits seasonal variations globally.
• These patterns appear to differ across various populations worldwide.

Purpose of the Study:

• To analyze the global monthly frequency of breast cancer diagnoses.
• To investigate the relationship between breast cancer seasonality, latitude, and demographic factors.

Main Methods:

• Examined monthly breast cancer diagnosis data for 2,921,714 cases across 64 regions.
• Analyzed data spanning 2 to 53 years, considering latitude and population characteristics.

Main Results:

• Breast cancer diagnoses consistently peak in spring and fall in both hemispheres.
• Seasonality intensifies with increasing distance from the equator, particularly in rural populations.
• Annual breast cancer incidence increased with latitude.

Conclusions:

• Breast cancer discovery is non-random, with peaks near equinoxes and valleys near solstices.
• Latitude-dependent seasonality suggests links to changes in day/night length, vitamin D, and melatonin.
• Understanding this seasonality can improve breast cancer prevention, screening, diagnosis, and treatment.