Global breast cancer seasonality.

Human breast cancer incidence has seasonal patterns that seem to vary among global populations. The aggregate monthly frequency of breast cancer diagnosis was collected and examined for 2,921,714 breast cancer cases diagnosed across 64 global regions over spans from 2 to 53 years. Breast cancer is consistently diagnosed more often in spring and fall, both in the Northern and Southern Hemispheres, regardless of presumable menopausal status (50).