5.3.3 Colorectal Polyps
Colorectal polyps are small growths projecting from the mucous membrane of the colon or rectum.They may be sessile（attached by a base）or pedunculated（attached by a stalk），and may vary in size.Colorectal polyps may also be histologically classified as neoplastic or non-neoplastic.The neoplastic polyps are of primary importance because they harbor a malignant potential，which represents a stage in the development of colorectal cancer.
People who are over the age of 50 also have a higher risk of forming polyps in the colon.A diet low in fiber and calcium and high in protein is a major risk.Obesity，lifestyle and heredity are common factors.Smokers，people who consume a high-fat diet，and those who consume alcohol are also at higher risk.
It is essential to identify the polyps as early as possible when they can be removed in a simple outpatient procedure so as to prevent their progression into colorectal cancer.Although most neoplastic polyps do not evolve into cancer，it is well accepted that the majority of colorectal carcinomas evolve from adenomatous polyps.
Polyps are usually asymptomatic（without symptoms）and are discovered during routine physical examinations that include diagnostic testing or tests for blood in the stool.They can，however，cause rectal bleeding and intestinal bleeding.When polyps are detected，a colonoscopy may be ordered to rule out cancer.A biopsy of the polyp may be obtained or the polyp may be completely removed during the procedure.
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Task 5 Fill in the blanks with proper words.
1.The small growths projecting from the________of the colon or rectum are termed as polyps.
2.A benign tumor is hardly cancerous，while the________one is likely to develop into cancer.(https://www.daowen.com)
3.Colon cancer may be caused by a diet high in protein and/or________but low in fiber and calcium.
4.Obesity，high alcohol________，and smoking，are known to increase the risk of developing colorectal polyps.
5.In the early stage，the colorectal polyps can be excised in a simple________procedure.
6.People usually are unaware of their health problems before routine physical examinations because many diseases are often________in the early stage.
7.It is essential to test________sample in diagnosing medical conditions，such as inflammatory bowel disease，gastric or colon cancers，hemorrhoids etc.
8.A（n）________is an endoscopic examination performed to detect changes or abnormalities in the colon.
9.A（n）________，the removal and examination of a sample of tissue from a living body，is the common way to diagnose cancer.
10.It is believed that most colorectal carcinomas evolve from________polyps.