Facts About Cancer

Some concepts about cancer can be helpful when trying to understand suspected cancer clusters:

  • Cancer is the uncontrolled growth and spread of abnormal cells anywhere in the body. However, cancer is not just one disease; it is actually a term for at least 100 different but related diseases.

  • Each type of cancer has certain known and/or suspected risk factors associated with it. Common risk factors are tobacco use, diet, heredity, and sun exposure.

  • Cancer is not caused by injuries, nor is it contagious. It cannot be passed from one person to another like a cold or the flu.

  • Cancer is almost always caused by a combination of factors that interact in ways that are not yet fully understood.

  • Carcinogenesis (the process by which normal cells are transformed into cancer cells) involves a series of changes within cells that usually occur over the course of many years. More than 10 years can go by between the beginning of carcinogenesis and the diagnosis of cancer, which makes it difficult to pinpoint the cause of the cancer.

  • Cancer is more likely to occur as people get older; because people are living longer, more cases of cancer can be expected in the future. This may create the impression of an abnormally high number of cases of cancer.

The National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program estimates that there are more than 8 million cases of cancer in the United States. Therefore, it is not unusual for several cases to occur within the same family or neighborhood.