Colorectal cancer is the second most deadly tumor in human beings.
In men, it ranks behind lung and prostate cancer in overall mortality, while in women it follows lung and breast malignancies. Colorectal cancer with regional or distant spread carries a poor prognosis. However, if the malignancy is detected early it has a greater chance of being surgically cured. Colorectal cancer is an ideal candidate for screening because of the curability and high prevalence of early tumors. Colorectal cancers arise from pre-malignant polyps.