Cancer is a group of diseases characterized by uncontrolled growth and spread of abnormal cells. If the spread is not controlled, it can result in death. Cancer is caused by other external factors (tobacco, infectious organisms, chemicals, and radiation) and internal factors (inherited mutations, hormones, immune conditions, and mutations that occur from metabolism). These causal factors may act together or in sequence to initiate or promote carcinogenesis. Ten or more years often pass between exposure to external factors and detectable cancer. Cancer is treated with surgery, radiation, chemotherapy, hormone therapy, biological therapy, and targeted therapy.
According to the American Cancer Society, half of all men and one-third of all women in the United States will develop cancer during their lifetimes. About 1.5 million new cancer cases are diagnosed each year (not including noninvasive cancer of any site except the urinary bladder, nor the annual diagnosis of more than 1 million cases of basal and squamous cell skin cancers).