Colorectal cancer, also called colon cancer or bowel cancer, includes cancerous growths in the colon, rectum and appendix. It is the third most common form of cancer and the second leading cause of death among cancers in the Western world. Many colorectal cancers are thought to arise from adenomatous polyps in the colon. These mushroom-like growths are usually benign, but some may develop into cancer over time. Diagnosis is by colonoscopy. Therapy is usually through surgery, with many cases also requiring chemotherapy.

Symptoms
Symptoms of colorectal cancer include:
Change in bowel habits.
Blood in stools (melena, hematochezia).
Bowel obstruction (rare) by the tumor
Often, the symptoms are much less specific:
Unexplained weight loss.
Anemia, with symptoms such as tiredness, malaise, pallor
Hepatomegaly (enlargement of the liver) due to spreading of the tumor
It is also possible that there will be no symptoms at all. This is one reason why some recommend periodical screening for the disease.