In the U.S., lung cancer is the leading cause of cancer-related deaths for both sexes, followed by prostate cancer in males and breast cancer in females. For children younger than 15 years old, cancer is the second leading cause of death after accidents. Leukemia, brain cancer and cancer related to the endocrine system are the leading cancers in children in this age group. There are many types of cancer because cancerous cells can grow anywhere in the body. The location of the cancer and the type of tissue involved helps to give the disease a specific name, such as lung cancer, ovarian cancer, breast cancer and prostate cancer.
Cancer is a process with many steps.
Normally, the body' s repair systems can replace damaged sections of DNA, allowing the cell to recover. If the cell reproduces while the DNA is damaged, more abnormal cells can be made that may cause cancer. Usually, initiation by itself is not enough to produce cancer. The altered cells go through more changes that may require an additional substance called a promoter . A period of many years usually exists between the initiation of the cancer process and the onset of the symptoms.