Changes in bowel movements, such as diarrhea or constipation, that last more than a few days are symptoms of bowel cancer. Narrow, thin stools; rectal bleeding; dark stools or bloody stools; cramping and pain in the abdomen are symptoms as well, according to the American Cancer Society.
Weakness and fatigue, unintended weight loss and feeling the continued urge to defecate after a bowel movement are also symptoms, states the American Cancer Society.
In its earliest stages, bowel cancer, also known as colorectal or colon cancer, can present with no symptoms at all, states the American Cancer Society. Regular screenings for colorectal cancer after the age of 50 are recommended as cancers that are caught in the early stages, before there are symptoms, have not had a chance to spread and are easier to cure.
Other medical problems, such as hemorrhoids, irritable bowel syndrome, inflammatory bowel disease and infections, can also cause many of the same symptoms as bowel cancer, notes the American Cancer Society, which recommends an exam by a doctor for any symptoms that last for more than a few days. Tests a doctor may perform include blood tests for cancer, x-ray or computed tomography scans of the colon, and a colonoscopy with or without a biopsy.