[MOL] Colon cancer and polyps/educational [00540] Medicine On Line


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[MOL] Colon cancer and polyps/educational



I hope you find this helpful.
Love Mam
The website this came from is:
http://www.maxinet.com/mansell/polyp.htm





COLON POLYPS & COLON CANCER©




By Donald E. Mansell, MD
Board Certified Gastroenterologist
153 Pearson Rd. 
Paradise, CA 95969 USA 
Phone 916-877-0400
ContentsWhat Are Polyps?What About Colon Cancer?Why Do polyps and Colon
Cancer Occur?How Quickly Do Polyps and Cancer Grow?So In Summary Who Is At
Increased Risk For Colon Cancer Needing Colonoscopy?What are the Symptoms
of Colon Cancer?How Can I Prevent Colon Polyps and Colon Cancer?Diagnosis
of Colon CancerFecal Occult Blood Testing ( FOBT )Flexible
SigmoidoscopyColonoscopyBarium EnemaScreening for Colon Cancer.What If I
Have Been Diagnosed With Colon Cancer?Staging of Colon CancerDuke's
ClassificationPrognosisHow Is Colon Cancer
Treated?EvaluationReferencesCreditLinksHome PageAbout the author



What Are Polyps?






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. During 1996 there were an
estimated 133,500 new cases of colorectal cancer ( CRC ) and about 54,900
deaths from ( CRC ). The strongest risk factor for colon cancer is age. The
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 wheat bran and
calcium can reduce the risk of colorectal cancer. An even more potent agent
in preventing colon cancer is the eating of vegetables. It isn't known yet
whether it is the fiber which binds to carcinogens and moves the
carcinogens out of the colon more rapidly or phytochemicals which 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. Obesity and inactivity 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
cancerPersons with a sibling, parent or child with colon cancerPersons who
are passing frank blood in the stoolMen with iron deficiency anemiaWomen
after menopause with iron deficiency anemiaPersons 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. DHEA ( dehydroepiandrosterone ), a
hormone produced by the adrenal, appears to interfere with G6PD ( an enzyme
) activity and at least in animal models prevents colon cancer ( this has
not been shown yet in humans ). 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, Hemocculttm, Hemoquant,tm
Hemoccult Sensatm, Hemewipestm, 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
Sarantm 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 Sarantm 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, trained Physician's Assistant or
trained Registered Nurse Practitioner. With the high sensitivity and
specificity of this test, along with its low complication rate,
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. Although some don't
go through with the test because of ignorance or misconceptions given them
by others. This is a 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. 



Diagnostic colonoscopy should be done as mentioned above in the following
situations:


INDICATIONS FOR COLONOSCOPY
Positive FOBTPolyp ( adenomatous ) on Flex Sig or Barium EnemaUnexplained
Iron Deficiency Anemia in a man or in a post menopausal womanFrank rectal
bleeding which does not appear to be coming from the anus or melena which
doesn't appear to be coming from Upper GI tractFlexible Sigmoidoscopy
showing Chronic Ulcerative Colitis ( CUC ) extending above the reach of the
Flex SigBarium 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 polypsClinically significant
diarrhea of unexplained originIntraoperative 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. 





The currently recommended surveillance regimen is as follows:


Indication for SurveillanceAction 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
----->>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 CLASSIFICATIONEXTENT OF INVASION LYMPH NODE
INVOLVEMENTPROGNOSISDuke's ALimited to the mucosaNone5 year survival
>90%Duke's B1into muscularis propriaNo lymph node involvement5 year
survival 70-85%Duke's B2through muscularis propriaNo lymph node
involvement5 year survival 55-65%Duke's C1into muscularis propriaLymph node
involvement is present5 year survival 45-55%Duke's C2through muscularis
propriaLymph node involvement is present5 year survival 20-30%Duke's
Ddistant metastases not applicable5 year survival 



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. 

<Picture>




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for Training and Practice. ASGE. 1990. 






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



Donald E. Mansell, MD

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

Steve Reisman Web Development Consultant

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Mansell Media Home Page


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Last updated: 

Sunday, December 22, 1996

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