<unk>  may be divided into preventable and non-preventable. Their study belongs in the field of epidemiology. Breast cancer, like other forms of cancer, can result from multiple environmental and hereditary<unk><unk> . The term "environmental", as used by cancer researchers, means any<unk> <unk> that is not genetically inherited. For breast cancer, the list of environmental<unk><unk>  includes the individual person's development, exposure to microbes, "medical interventions, dietary exposures to nutrients, energy and toxicants, ionizing radiation, and chemicals from industrial and agricultural processes and from consumer products...reproductive choices, energy balance, adult weight gain, body fatness, voluntary and involuntary physical activity, medical care, exposure to tobacco smoke and alcohol, and occupational exposures, including shift work" as well as "metabolic and physiologic processes that modify the body's internal environment." Some of these environmental<unk>  are part of the physical environment, while others (such as diet and number of pregnancies) are primarily part of the social, cultural, or economic environment. Although many epidemiological<unk><unk>  have been identified, the cause of any individual breast cancer is most often unknowable. Epidemiological research informs the patterns of breast cancer incidence across certain populations, but not in a given individual. Approximately 5% of new breast cancers are attributable to hereditary syndromes, and well-established<unk><unk>  accounts for approximately 30% of cases.
Risk factors for breast cancer
Cardiovascular disease in women
Pre-cancer of the breast
Age and female fertility
Thyroid disease in women
Autoimmune disease in women
Sexually active life expectancy
Menopause, Estrogen and Venous Events