Physiological Effects of Exercise on Breast Cancer Risk• Decreased Lifetime Exposure to Endogenous Estrogen
• Decreased Number of Menstruations/Ovulations
• Decreased Level of Ovarian Estrogen Production
• Decreased Levels of Endogenous Estrogen in Blood
• Less Conversion of Androgen to Estrogen in Fat Cells
• Decreased Breast Density
• Risk Four Times Lower with Less Breast Density
• Increased Immune Function
• Increased Natural Killer Cells Fight Tumor Initiation
--American College of Sports Medicine
