Cancer is a group of diseases in which abnormal aggressive cells divide without control and can spread to other tissues through the lymph vessels or blood. Almost all cancers are due to abnormalities in the genetic code of the changed cells. Usually old or damaged cells have to be replaced by new cells as a person needs them. Sometimes this process looses control, meaning new cells grow even when the body does not ask for them, and old cells don't die when they should. The accumulation of extra cells form a tumor. Tumors can be benign or malignant (cancer). Odor from cancer and tumors depends on the area they are located. If the tumor/cancer is in the oral cavity, lungs, stomach, liver or intestines, it may cause bad breath. A tumor/cancer from the cervix or uterus may produce a discharge with a distinctive smell. Leukemia and lymphoma can produce excessive sweating.