COLON POLYPS & COLON CANCER©

By Donald E. Mansell, MD
Board Certified Gastroenterologist
153 Pearson Rd.
Paradise, CA 95969 USA
Phone 530-877-0400

Polyps are growths which develop in the colon and other parts of the body as well. They vary in size and appearance. They may look like a wart when small and when they grow they may appear like a cherry on a stem or fig. They are important because they can with time turn into cancer. Sometimes they can bleed causing anemia. A polyp is defined as a growth that projects, often on a stalk, from the lining of the intestine or rectum. Polyps of the colon and rectum are almost always benign and usually produce no symptoms. They may, however, cause painless rectal bleeding or bleeding not apparent to the naked eye. There may be single or multiple polyps. The incidence of polyps increases with age. The cumulative risk of cancer developing in an unremoved polyp is 2.5% at 5 years, 8% at 10 years, and 24% at 20 years after the diagnosis. The probability of any singular polyp becoming cancerous is dependent on its gross appearance, histologic features, and size. The relative risk of developing colon cancer after polyps have been removed is 2.3 compared to a relative risk of 8.0 for those who do not have the polyps removed. Polyps greater than 1 centimeter have a greater cancer risk associated with them than polyps under 1 centimeter. Polyps with atypia or dysplasia are also more likely to progress on to colon cancer. The risk of cancer is much higher in sessile villous adenomas than in pedunculated tubular adenomas. Cancer is found in 40% of villous adenomas, as compared to 15% in tubular adenomas. The good news is that 65% of adenomas are tubular, with villous adenomas accounting for only 10% of adenomatous polyps. It has been shown that the removal of polyps by colonoscopy reduces the risk of getting colon cancer significantly.

What About Colon Cancer?

Don't panic! Colon cancer has an excellent cure rate. Colon cancer is a very common cancer second only to lung cancer. 129,400 new cases of colorectal cancer are estimated for 1999 with 56,600 deaths from CRC. The strongest risk factor for colon cancer is age. The (Current Statistics on CRC)incidence rates rise from 10 per 100,000 at age 40-45 to 300 per 100,000 at age 75-80. The cumulative life time risk for the disease is 1 in 20. Men are more likely to develop Colon Cancer than women. Black Americans are more likely than White Americans to be diagnosed with colorectal cancer. Smokers, drinkers, sedentary and obese persons are more likely to develop colon cancer.

Why Do polyps and Colon Cancer Occur?

Both polyps as well as colon cancer occur much more frequently in industrialized, western societies. Diets low in fruits, vegetables, protein from vegetable sources and roughage are associated with a higher incidence of polyps. Persons smoking more than 20 cigarettes a day are 250% more likely to have polyps as opposed to nonsmokers who otherwise have the same risks. Persons who drink have an 87% increased likelihood of having polyps compared to nondrinkers and those who both smoke and drink are 400% more likely to develop polyps compared to their peers who neither smoke nor drink. There is increasing evidence that diets high in calcium can reduce the risk of colorectal cancer. An even more potent agent in preventing colon cancer is the eating of vegetables. Apparently it isn't the fiber but it is likely that phytochemicals in vegetables act to prevent cancer. People who exercise daily are less likely to develop colon cancer. Polyps tend to cluster in families so that having a first degree relative ( sibling, parent or child ) with colon polyps raises ones chances of having polyps. The familial cancer syndromes such as Lynch Syndromes I and II ( rare ) carry a high risk of the development of colon and other cancers. Family adenomatous polyposis or FAP, is a rare condition characterized by thousands of adenomatous polyps throughout the large bowel. People with 1st degree relatives with inflammatory bowel disease are at increased risk and those who have a first degree relative with colon cancer have a fourfold increase in risk over the general population and should be screened earlier with colonoscopy and more often than the proposed outline for screening suggested by the American Cancer Society. There is an association of cancer risk with meat, fat or protein consumption which appear to break down in the gut into cancer causing compounds called carcinogens. A personal history of ovarian, endometrial, or breast cancer also appear to be risk factors.

How Quickly Do Polyps and Cancer Grow?

It may take five years or more for a polyp to reach a 1/2 inch ( 1 cm ) in diameter. It generally takes a 1/2 inch polyp 5-10 years or more to turn into cancer. It will then take around 5-10 years for the cancer to cause symptoms by which time it is frequently too late.

So In Summary Who Is At Increased Risk For Colon Cancer Needing Colonoscopy?

PERSONS WITH ONE OR MORE OF THE FOLLOWING ARE AT RISK FOR COLON CANCER

Woman who have been diagnosed with breast or ovarian or uterine cancer	Persons with a sibling, parent or child with colon cancer	Persons who are passing frank blood in the stool
Men with iron deficiency anemia	Women after menopause with iron deficiency anemia	Persons found on screening exams to have blood present in the stool

What are the Symptoms of Colon Cancer?

The reason that screening in asymptomatic individuals is so important is that most persons who have colon cancer have either no symptoms or very nonspecific symptoms until the cancer has become advanced.

Right sided, ascending colon tumors often present with fatigue, weakness, and anemia of iron deficiency of unknown origin. These lesions can grow quit large without causing any obstructive symptoms because stool in the ascending colon is relatively liquid and can continue to pass through even significantly narrowed lumens. Lesions of the ascending colon often project into the lumen and ulcerate, causing chronic blood loss resulting in symptoms of palpitations, possible angina pectoris, as well as fatigue. Any adult presenting with chronic iron deficiency of unknown origin should have a through visualization of the entire bowel via colonoscopy.

Since stool in the left descending colon is more formed, symptoms of obstruction are often the first presenting symptoms. Such symptoms include changes in bowel habits ( constipation and/or diarrhea ), crampy left lower quadrant pain and even perforation. Barium enema X-rays of left sided lesions often reveal characteristic annular, constricting lesions.

How Can I Prevent Colon Polyps and Colon Cancer?

The incidence of colon cancer is higher in active smokers compared to those who have stopped smoking, hence smoking cessation is important for those who wish to decrease their likelihood of developing colon cancer. Aspirin taken daily reduces not only the incidence of both colon polyps and colon cancer but of cancer of the stomach and esophagus as well. It is felt that one coated adult aspirin ( 325 mg ) daily is adequate for the purpose of preventing colon cancer. Aspirin interferes in prostaglandin metabolism and this seems to be the mechanism for it preventing cancer as well as cardiovascular disease. It must be remembered that aspirin can cause GI upset, ulcers and bleeding among other things. Dietary supplementation with 1500 mg of Calcium or more a day is associated with a lower incidence of colon cancer. Weight reduction may be helpful in reducing the risk for colorectal cancer. Daily exercise reduces the likelihood of developing colon cancer. Selenium and other antioxidants may be in the future be found helpful in reducing colon cancer risk. Tumeric, the spice which gives curry it's distinctive yellow color, may also prevent colon cancer.

Diagnosis of Colon Cancer

The diagnosis of colon cancer depends on a variety of methods including barium enema, sigmoidoscopy, colonoscopy and biopsy once a mass is found.

Fecal Occult Blood Testing ( FOBT )

Other names include: Occult Blood Testing, Hemoccult^tm, Hemoquant,^tm Hemoccult Sensa^tm, Hemewipes^tm, etc.

This is a test that detects the presence of occult ( detectable only by chemical means and not visible ) blood in the stool. Such blood may arise from anywhere along the digestive tract but is most likely to originate in the colon.

There are many ways to collect the samples. You can catch the stool on Saran^tm wrap that is loosely placed over the toilet bowel and held in place by the toilet seat. Then put the sample in the clean container supplied or on the card which was given you. One test kit, Hemewipes ^tm, supplies a special toilet tissue that you use to collect the sample, then put the sample in a clean container. For children wearing diapers, you can line the diaper with Saran^tm wrap.

Laboratory procedures vary. In one type of test, a small sample of the stool is placed on a special paper "card". A drop or two of testing solution is applied to a positive and negative control at the bottom of the card. A color change ( often blue ) indicates the presence of blood in the stool.

Do not consume red meat or fish ( contain non-human hemoglobin ) for 3 days as this can cause a false positive reading for blood. Discontinue drugs and substances that can interfere with the test such as: Vitamin C which can cause a false negative reading; Horse radish, fresh broccoli, turnips, cauliflower ( have vegatable peroxidase ) and colchicine which can give a false positive reading; Anticoagulants, Aspirin or arthritis medicine which can cause leakage of blood into the intestinal tract; Oxidizing drugs such as topical iodine, bromides, and boric acid, and reserpine need to be stopped about three days before the test as they can cause a false positive reading.

Flexible Sigmoidoscopy

Flexible sigmoidoscopy can reach as high as the descending colon and can be done by a trained Primary Care Physician. Sigmoidoscopy has been proven to reduce the incidence and mortality of colon cancer through early detection. Flexible sigmoidoscopy however, is not an adequate method of screening in hereditary colon cancer as 2/3 of the lesions develop proximal to the splenic flexure. In these cases colonoscopy should be used. Flexible Sigmoidoscopy ( Flex Sig ) is done without sedation usually in the practitioner's office. Flexible sigmoidoscopy can detect about 65%­75% of polyps and 40%­65% of colorectal cancers. This test, for an investment of 3-5 minutes, can with little discomfort reduce the likelihood of your developing colon cancer and if colon cancer is present detecting it at an early, highly curable stage.

Colonoscopy

Colonoscopy remains the gold standard for visualization, biopsy and removal of colonic polyps. The removal of all polyps by colonoscopy has been demonstrated to reduce the risk of colon cancer by 76 to 90 percent. In 1994 over 2,000,000 colonoscopies were performed in the US and over 650,000 of these underwent polypectomy.

INDICATIONS FOR COLONOSCOPY

Positive FOBT	Polyp ( adenomatous ) on Flex Sig or Barium Enema	Unexplained Iron Deficiency Anemia in a man or in a post menopausal woman
Frank rectal bleeding which does not appear to be coming from the anus or melena which doesn't appear to be coming from Upper GI tract	Flexible Sigmoidoscopy showing Chronic Ulcerative Colitis ( CUC ) extending above the reach of the Flex Sig	Barium enema or Flex Sig showing nonobstructing colorectal cancer. Colonoscopy should be done prior to surgery to make sure there are no synchronous colorectal cancers or large polyps
Clinically significant diarrhea of unexplained origin		Intraoperative identification of the site of lesion that cannot be detected by palpation or gross inspection at surgery
	*In selected Duke's C patients one may consider following Chest X-rays and serum CEA's ( carcinoembyonic antigen- a blood test that detects a substance that rises in some cancers such as colon and pancreatic cancer ) providing there was a postoperative drop in the CEA every 2-3 months for 2 years. Surveillance colonoscopy is not indicated in this patient population.

Indication for Surveillance		Action to Be Taken
One 1st degree relatives with colorectal cancer who developed the cancer at age 55 or over.		Yearly Fecal Occult Blood Testing ( FOBT )and a Flex Sig beginning at age 35-40 followed by a Flex Sig every 5 years.
One 1st degree relatives with colorectal cancer who developed the cancer before age 55.		Colonoscopy beginning at age 50 then every 5 years thereafter along with yearly FOBT.
Two 1st degree relatives with colorectal cancer.		Colonoscopy beginning at age 35 ( or 5 years younger than the earliest case in the family ) then every 5 years thereafter along with yearly Fecal Occult Blood Testing ( FOBT ).
Three or more 1st degree relatives with colorectal cancer.		Colonoscopy beginning at age 35 (or 5 years younger than the earliest case in the family then every 3-5 years thereafter along with yearly Fecal Occult Blood Testing ( FOBT).
One or more 2nd degree relatives with colorectal cancer.		Yearly Fecal Occult Blood Testing ( FOBT )and a Flex Sig beginning at age 50 followed by a Flex Sig every 5 years.
One 1st degree relative and one 2nd degree relative with colorectal cancer.		Colonoscopy beginning at age 50 then every 5 years thereafter.
1st degree or 2nd degree relatives with adenomatous polyps.		Yearly FOBT and a Flex Sig beginning at age 50 followed by a Flex Sig every 5 years.
Hereditary nonpolyposis colorectal cancer.		Colonoscopy beginning at age 25 with subsequent colonoscopies every 2-3 years.
Following the removal of an adenomatous polyp <1 cm in size.		Further surveillance may not be needed. It would be prudent to follow these individuals with yearly FOBT and Flex Sig every 5 years.
Following the removal of multiple polyps with suboptimal clearing the first time.		Repeat colonoscopy at 1 year and again at 4 years.
After one negative 3 year follow-up colonoscopy.		Subsequent surveillance colonoscopy may be done every 5 years.
8 years after the diagnosis of universal chronic ulcerative colitis ( CUC ) .		Subsequent surveillance colonoscopies are done every 1-2 years unless dysplasia is present.
Low grade dysplasia found on colonoscopy in a patient with universal CUC.		Colonoscopy at 6 months and if no dysplasia is present then colonoscopy every year.
12-15 years after the diagnosis of left-sided CUC.		Subsequent surveillance colonoscopy may be done every 2 years thereafter.
Following resection of a colorectal carcinoma.		Colonoscopy every 3-5 years when a colonoscopy has been done preoperatively. If Colonoscopy has not been done preoperatively then colonoscopy should be done 3-6 months after colon resection if no distant metastases were found at time of surgery.
Crohn's colitis ( especially when pANCA is positive ) colonoscopy 12-15 years after initial diagnosis.		Subsequent surveillance colonoscopy may be done every 2 years thereafter.
	*In selected Duke's C patients one may consider following Chest X-rays and serum CEA's ( providing there was a postoperative drop in the CEA ) every 2-3 months for 2 years.

Barium Enema

Enthusiasm for the double contrast barium enema has declined in recent years in favor of colonoscopy, despite its lower cost. The reason for this decrease in use as a diagnostic tool lies in the reduced sensitivity of this test in detecting polyps of less than 1 cm, in detecting polyps in areas where a single lumen is not detectable ( i.e. sigmoid, rectosigmoid, hepatic and splenic flexures ) and patient comfort and compliance issues. Despite these limitations, when a colonoscopy is not possible the double contrast barium enema when combined with a flexible sigmoidoscopy is an acceptable alternative, with the exception of surveillance familial polyps, familial colon cancer and inflammatory bowel disease, where attention to small details of the colonic mucosa is required and the likelihood of biopsy or polyp removal is high.

Screening for Colon Cancer

Current screening procedures suggested by the American cancer society include annual digital rectal examination beginning at age 40, annual fecal hemoccult screening starting at age 50 and sigmoidoscopy every 3-5 years beginning at age 50 for symptomatic individuals having none of the high-risk factors for colorectal carcinoma. For those with high risk factors screening should be done more often and at an earlier age depending on the risk factor involved. It is evident that better screening methods are needed as only 38% of colon cancers are localized at the time of diagnosis. If polyps are found on Flexible Sigmoidoscopy or on a Barium Enema, Colonoscopy will usually be performed to remove the polyps and to make sure that there aren't any other undetected polyps or cancer. Screening of patients by use of carcinoembryonic antigen or CEA is not recommended because it generally rises after the tumor is large and has spread. It is not specific for colon cancer and it can rise without having a cancer in smokers.

What If I Have Been Diagnosed With Colon Cancer?

( Prognosis )

The prognosis of survival directly correlates with the stage of the colon cancer at the time of diagnosis. The 5 year survival rates are given according to the Duke's classification.

Most recurrences after surgical resection occur within the first 4 postoperative years.

Dukes Classification

DUKE'S CLASSIFICATION	EXTENT OF INVASION	LYMPH NODE INVOLVEMENT	PROGNOSIS
Duke's A	Limited to the mucosa	None	5 year survival >90%
Duke's B1	into muscularis propria	No lymph node involvement	5 year survival 70-85%
Duke's B2	through muscularis propria	No lymph node involvement	5 year survival 55-65%
Duke's C1	into muscularis propria	Lymph node involvement is present	5 year survival 45-55%
Duke's C2	through muscularis propria	Lymph node involvement is present	5 year survival 20-30%
Duke's D	distant metastases	not applicable	5 year survival <1%

Poor prognostic indicators include:

1) 5 or more lymph nodes involved. 2) Tumor spread to regional lymph nodes. 3) Tumor penetration through the bowel wall. 4) Perforation of colon. 5) Tumor adherence to adjacent organs. 6) Metastasis to distant organs. 1-6 all put the patient in a more advanced staging category. Some other poor prognostic signs not reflected directly by staging are: 7) Poorly differentiated histology. 8) Venous invasion of tumor. 9) Preoperative elevation of CEA titer greater than 5.0 ng/ml.. 10) P53 mutation found in tumor. 11) DNA aneuploidy

Distant metastases is one of the worst prognostic signs as this places the patient in the most advanced staging category. Cancers of the large bowel generally spread through the lymphatics or through the portal venous system to the liver. The liver is the most frequent visceral site of metastatic dissemination and is the initial site of distant spread in one-third of recurring colon cancers, with two-thirds of patients having liver involvement at the time of death. Other commonly involved sites for metastatic spread when the liver is involved are lung and bone and brain. Rarely are the lung, bone, or brain involved without liver involvement. The median survival after the detection of distant metastases range from 6 to 9 months ( with heavy liver involvement ) to 24 to 30 months ( with initially small liver nodules ). The work up to detect metastatic spread after a primary colon tumor is diagnosed may include: liver function tests, abdominal CT to evaluate intra-abdominal extra colonic involvement, chest x-ray and/or chest CT for lung nodules, and a bone scan when indicated by new onset of bony pain.

How Is Colon Cancer Treated?

The surgical resection of colon cancer with 3-5 cm disease free margins and resection of the mesentery at the origin of the blood supply, including primary lymphatic drainage sites, is required treatment to attempt a cure of the disease. Usually colostomy(where the colon is brought out through the abdominal wall requiring the placement of a bag to drain the stool) can be avoided unless the cancer is too low ( usually less than 5 cm from the anus ).

Cure can be achieved with surgery alone in a large number of patients. When the cancer is detected at an earlier stage ( this is why screening is needed ) the cure rates are much higher. Overall 75% of patients ( Duke's A and B1 ) are cured by a primary resection and of the 25% of patients who develop a recurrence, 20% of these will be cured by a second resection.

Today, adjuvant therapy is standard for patients with stage TNM 3 or Duke's B2 and C colon cancer. A combination of 5-FU ( 5-fluorouracil ) and levamisole is used in stage TNM 3 or Duke's C over a duration of 1 year postoperatively and is combined with radiation therapy for Duke's stage B2 and TNM stage 4. Adjuvant therapy with 5-FU and Levamisole have been shown to increase the overall survival in patients with TNM stage 3 colon cancer, over those treated by surgery alone, from 46% to 60% after 6.5 years.

REFERENCES

Caveat

THIS INFORMATION IS NOT A SUBSTITUTE FOR SEEING YOUR PRIMARY CARE PRACTITIONER AND OBTAINING APPROPRIATE ADVICE. THIS INFORMATION IS NOT TO BE CONSIDERED AS A COMPREHENSIVE REVIEW NOR ARE THE REFERENCES COMPLETE. THIS PAGE IS FOR EDUCATIONAL PURPOSES ONLY. YOU MAY USE THIS FOR NON COMMERCIAL PURPOSES. INCLUDE THIS MESSAGE IN THE COPY AND INCLUDE THE CREDIT.

Evaluation

---

- Last Name - First Name - Middle Name - Occupation - How did you find this Website? - Which Search Engine did you use? - Email Address Is this a Website you could recommend to others? Yes No Was this website useful to you? Yes No - Your Web Site Address -Hot GI Links You Might Suggest(URL) Where do you presently reside? - City - Province or State - Country Your Suggestions for This Website - Comments: - Additional Comments: - Additional Comments: This is information useful for improving this website. The information you provide will remain confidential.

---

---

Excellent Webpages Related to GI Problems

---

ASK ASGE - Very Helpful Information with Pages Explaining GE Conditions and Endoscopic Procedures

---

Useful Digestive Diseases Related Websites

The DAVE Project an Extensive Collection of Endoscopic Videos, Powerpoint Presentations and Podcasts Inspired by William Brugge, MD, FASGE - Hosted by Massachussetts General Hospital & Harvard University

---

Centers for Disease Control and Prevention Fact Sheet on Colon Cancer

NIH Digestive Diseases Website
Center for Digestive Health and Nutrition
Gastroenterology Consultants, PC


Gastroenterology Professional Society Websites

American College of Gastroenterology

American Gastroenterolologic Association

Canadian Association of Gastroenterology

---

Ulcerative Colitis and Crohn's Disease

CCFA -- Crohn's & Colitis Foundation of America

More on Cancer

Oncolink

Search Engines

---

---

---

---

---

---

Programmed in HTML & Copyright© 10/13/96 by:

Donald E. Mansell, MD

Special thanks to Steve Reisman for his valuable input on Webpage design

---

Picture of the author

---

Mansell Media Home Page

---

Last updated: Thursday, April 28, 2006

---