Cancer is defined as the uncontrollable proliferation of abnormal cells in any part of the body. There are more than 200 different forms of cancer. Cancer can be caused by anything that causes a normal body cell to develop abnormally; major categories of cancer-related or causative agents include chemical or toxic substance exposures, ionizing radiation, certain infections, and human genetics. Cancer symptoms and signs vary depending on the type and grade of cancer; however, the following can be seen in patients with various cancers: fatigue, weight loss, pain, skin changes, change in bowel or bladder function, unusual bleeding, persistent cough or voice change, fever, lumps, or tissue masses. Although there are several methods to screen and presumptively diagnose cancer, a biopsy sample of probable cancer tissue is used to make a definitive diagnosis. Biopsy results are frequently used to assess cancer staging, which aids in determining the type of cancer and the amount to which it has spread; staging also aids caretakers in determining treatment procedures. In general, the higher the number allocated (typically between 0 and 4) throughout most staging approaches, the more aggressive the cancer type or the more extensive the cancer in the body. Staging procedures range from cancer to cancer and must be reviewed with your health care professional on an individual basis.