Symptoms of black stool cancer, or bowel cancer, include bloody stools, a change in bowel habits, weight loss and a cancerous lump, reports Cancer Research UK. An abnormally low level of red blood cells, or anemia, may be present as well.
Bowel cancer, or colorectal cancer, does not have an exact identified cause, according to WebMD; however, there are several risk factors for colorectal cancer. They include the presence of other diseases, such as Crohn's disease and cancers of the pancreas and female reproductive organs; heredity; diets rich in saturated fat and protein; chemical exposure; history of colon cancer; smoking and alcohol intake; exposure to radiation; and a history of certain types of surgeries. Another factor that increases the risk of developing colorectal cancer risk is hereditary nonpolyposis colon cancer, or Lynch Syndrome, which is a disease passed from generation to generation that causes people to develop colon cancer.
Stomach cancer also results in black, bloody stools, according to NHS Choices. Early stage symptoms of stomach cancer include perpetual indigestion, difficulty swallowing, heartburn, frequent gas and frequent feelings of being bloated and full very quickly. Vomiting and pain in the stomach may occur as well. Stomach cancer also presents distinct symptoms in advanced stages, including black stools, weight loss, loss of appetite, exhaustion, jaundice and swelling of the stomach.