In addition to spreading to surrounding areas, cancer can also spread to distant sites by the blood and lymphatic circulation and so can produce invasive tumors in almost any part of the body. In 1997, approximately 1,500,000 people in the United States were diagnosed with cancer and approximately 600,000 died of the disease. Early screening for cancer is believed to be able to drastically reduce the number of deaths due to the disease. Knowing what to look for when detecting cancer, as well as knowing if you are in a high risk population are two aspects of early prevention which have been proven to increase survival rates and lower the length and severity of treatments.