A soreness of the throat or a persistent cough. A persistent cough is one of the initial symptoms of throat cancer. If the cough becomes chronic, it could indicate, instead, a cancer of the lung or of some other region of the body, including the thyroid or the larynx. Since a cough is a fairly common symptom of a number of innocuous respiratory diseases, the gauge of its severity is how long it lasts. A cough that goes away in a little while is nothing more than a mild respiratory disorder, such as a cold. However, a cough that is chronic and persists for a long time is definitely a symptom of something more serious.