A persistent cough is a possible sign of lung cancer, according to the American Cancer Society. Hoarseness can signal cancer of the thyroid or larynx. However, a persistent cough is not a definitive sign of cancer; the symptom could be caused by many other conditions. A doctor should evaluate a patient to check for additional symptoms of cancer.
Other possible signs and symptoms of cancer include unexplained weight loss, fever, fatigue, pain and skin changes, notes the American Cancer Society. Changes in bladder function or bowel habits, sores that do not heal, white patches inside the mouth, unusual bleeding or discharge, and difficulty swallowing are other signs of specific cancers, such as bladder, kidney or stomach cancers. All of these symptoms are not definitive signs of cancer and should be evaluated by a doctor.
Cancer is caused by abnormal cells that begin to grow out of control and invade other tissues, explains the American Cancer Society. Abnormal cells have DNA damage that prevents cell death. Instead, the cells continue to grow and create new cells that also have this damaged DNA. Cancer cells often spread throughout the body via the bloodstream and lymph vessels. While some cancers are genetic or can be linked to a direct cause, there is no known cause for many other cancers.