Overview
Breast cancer epidemiologyBreast cancer is the most frequently diagnosed non-skin malignancy in women in the United States, with 213,910 cases expected in 2004, 1 and its incidence is gradually increasing. A woman who lives to be 90 years old has a 1 in 8 risk of being diagnosed with breast cancer in the United States. 2 Despite focused efforts over the last few decades to further understand the causes of breast cancer, little new information has been gained regarding its etiology. Risk factors that are "known" explain only approximately 40% of the variability in incidence. 3 The rest of the remaining risk for breast cancer remains a speculative or unknown realm. Estrogen exposure (e.g., early age at menarche, no or few children, late first full-term pregnancy, and hormone replacement therapy), family history of breast cancer, alcohol consumption, and physical activity have been considered as important risk factors, while data on other risk factors are inconsistent, including the potential effects of diet, smoking, and environmental factors on breast cancer risk. 4
Oxidative stress in breast cancer riskThere is increasing evidence indicating that oxidative stress is involved in the pathogenesis of breast cancer. Exposures from endogenous and exogenous oxidant sources constantly produce reactive oxygen species (ROS) 897 Oxidative Stress, Disease and Cancer Downloaded from www.worldscientific.com by LA TROBE UNIVERSITY on 06/11/16. For personal use only.