Polyp guideline: diagnosis, treatment, and surveillance for patients with
colorectal polyps.
SOURCE(S):
Am J Gastroenterol 2000 (11):3053-63 [108 references]
Diagnosis and Treatment
Colorectal polyps can be diagnosed by endoscopy or barium radiography. When
there is an indication to examine the entire large bowel, colonoscopy is the
diagnostic procedure of choice. It is the most accurate method of detecting
polyps of all sizes and it allows immediate biopsy or polypectomy. Most
polyps found during colonoscopy can be completely and safely resected,
usually using electrocautery techniques. Scientific studies now conclusively
show that resecting adenomatous polyps prevents colorectal cancer.
*         Single-contrast barium enema is an inaccurate method for detecting
polyps in most patients. Double-contrast techniques greatly improve the
accuracy of radiological methods for detecting polyps. However, even when
double-contrast methods are employed, barium enema examinations as they are
currently performed in most community hospitals are insufficiently sensitive
for the reliable detection of colorectal polyps. The other main limitations
of barium enema is that it does not allow biopsy or polypectomy, and it has
relatively low specificity (many false-positives) for polyps.
*         The most common use of flexible sigmoidoscopy is for screening
asymptomatic average-risk persons for colonic neoplasms. Sensitivity and
specificity are very high because few polyps within reach of the instrument
are missed, and the false-positive rate is negligible. The combination of a
double-contrast barium enema and flexible sigmoidoscopy has been promoted as
an acceptable alternative to colonoscopy for patients requiring a complete
examination of the large bowel in whom colonoscopy is incomplete or
unacceptable. When a barium enema is used for diagnosis or surveillance,
flexible proctosigmoidoscopy usually should be done to ensure an adequate
examination of the rectum. Flexible sigmoidoscopy also provides a more
accurate examination of the sigmoid colon, which is often a difficult area
for the radiologist to examine. Double-contrast barium enema seems to be
more accurate in the proximal colon than in the distal colon. Although
flexible sigmoidoscopy allows biopsy of lesions, it should not be used for
electrosurgical polypectomy unless the entire colon is prepared, to
eliminate the risk for electrocautery-induced explosion. Furthermore,
detection of a neoplastic polyp by screening flexible sigmoidoscopy is
usually an indication for colonoscopy, at which time the polyp can be
resected and a search made for synchronous neoplasia.
Management
Initial Management of Polyps
Most patients with polyps detected by barium enema or flexible
sigmoidoscopy, especially if the polyps are multiple or large, should
undergo colonoscopy to excise the polyp and search for additional neoplasms.
The decision whether to perform colonoscopy for patients with polyps <1 cm
in diameter must be individualized depending on the patient's age,
comorbidity, and past or family history of colorectal neoplasia. Complete
clearing colonoscopy should be done at the time of every initial polypectomy
to detect and resect all synchronous adenomas. Additional clearing
examinations may be required after resection of large sessile adenomas or
if, because of multiple adenomas or other technical reasons, the
colonoscopist is not reasonably confident that all adenomas have been found
and resected.
*         Most polyps diagnosed during colonoscopy can be completely removed
by electrocautery techniques. Surgical resection of a polyp is indicated
only when an experienced endoscopist is unable to resect an advanced adenoma
safely or when a malignant polyp requires colonic resection.
*         Most pedunculated polyps are resected by snare-polypectomy and the
entire specimen is submitted for pathological evaluation. A total excisional
biopsy is desirable so that the polyp can be properly classified and the
presence or absence of malignancy determined; and so that, for malignant
polyps, the grade, vascular and lymphatic involvement, and proximity to the
margin of resection of the cancer can be assessed.
*         Large sessile polyps usually require piecemeal snare resection;
but, again, every effort is made to retrieve all resected tissue for
pathological analysis. Injection of saline into the submucosa under a large
or flat sessile polyp (saline-assisted polypectomy) may increase the ease
and safety of snare-resection, especially in the right colon.
Management of Small Polyps
Small polyps (<1 cm) encountered during colonoscopy are usually resected
using one of a number of different techniques, with and without
electrocautery. The monopolar hot biopsy forceps has limitations and risks
that need to be carefully considered. Representative biopsies should be
obtained when small polyps are numerous. When a small polyp is encountered
during screening flexible sigmoidoscopy, it should be biopsied to determine
whether it is an adenoma and, thus, may be an indication for colonoscopy.
Current evidence supports the recommendation that a hyperplastic polyp found
during flexible sigmoidoscopy is not, by itself, an indication for
colonoscopy. Data are conflicting as to whether small distal adenomas
predict the presence of proximal clinically significant adenomas; therefore,
the decision to do colonoscopy must be individualized.
*         Small sessile polyps are resected using several different
techniques including hot and cold biopsy (with and without cautery), hot or
cold minisnare, or cold biopsy followed by fulgeration with a monopolar or
bipolar electrode. The monopolar hot biopsy forceps should be used with
great caution in the thin-walled right colon. There have been reported
perforations and a relatively high rate of delayed bleeding using this
device. When using any type of cautery probe in the right colon, it is
important to apply low-power cautery cautiously without pressing the tip of
the probe into the bowel wall. Even modest pressure can thin out the wall
and increase the chance of perforation.
A Small Polyp Found During Screening Flexible Sigmoidoscopy
*         When a polyp less than about 8 mm in size is detected during
screening flexible sigmoidoscopy, a biopsy usually should be done to
determine whether it is an adenoma. If the only abnormality found during
screening sigmoidoscopy is a hyperplastic polyp, no further evaluation or
follow-up is indicated. Most larger polyps (>0.7 cm) are adenomas;
therefore, there is usually no need to do a biopsy during screening
sigmoidoscopy.
*         The management of a patient found to have small tubular adenomas
at flexible sigmoidoscopy must be individualized. Colonoscopy to look for
synchronous adenomas, or for follow-up to search for metachronous neoplasia,
may be of little benefit to most patients with only one or two small (<1-cm)
tubular adenomas. Younger, healthy individuals may wish to have colonoscopy
to reduce their risk of cancer even below that of the average-risk
population. Older patients, especially those with significant comorbidity,
may not benefit from an intensive evaluation or follow-up.
The Small Flat Adenoma
*         Many recent papers describe small flat colorectal adenomas with a
purportedly high malignant potential. These reports suggest that such
lesions are common, may be missed during conventional colonoscopy, and
frequently and rapidly degenerate into small flat cancers. Most, but not
all, of the papers reporting these lesions have come from Japan and other
Eastern countries. They stress the need for special techniques employing
dye-staining chromoendoscopy, with or without magnification, to accurately
detect these lesions. Small flat adenomas with a high malignant potential
seem to be rare in Western countries, and there is little evidence that
early colonic cancer is a frequently overlooked entity in Western countries,
provided that patients undergo colonoscopy by well-trained, experienced
endoscopists. Modern high-resolution video endoscopy seems to detect most
clinically significant lesions without the need for special techniques.
Management of Large Sessile Polyps
A patient who has had successful colonoscopic excision of a large sessile
polyp (>2 cm) usually should undergo follow-up colonoscopy in 3 to 6 months
to determine whether resection was complete. If residual polyp is present,
it should be resected and the completeness of resection documented within
another 3 to 6-month interval. If complete resection is not possible after
two or three examinations, the good-risk patient should usually be referred
for surgical therapy.
Malignant Polyps
No further treatment is indicated after colonoscopic resection of a
malignant polyp (an adenomatous polyp with cancer invading the submucosa) if
the endoscopic and pathological criteria listed below are fulfilled.
Recommendations for a Patient With a Malignant Polyp
Because the risk for local recurrence or for lymph node metastasis from
invasive carcinoma in a colonoscopically resected polyp is less than the
risk for death from colonic surgery, the American College of
Gastroenterology recommends no further treatment if the following criteria
are fulfilled:
1.    The polyp is considered to be completely excised by the endoscopist
and is submitted in toto for pathological examination.
2.    In the pathology laboratory, the polyp is fixed and sectioned so that
it is possible to accurately determine the depth of invasion, grade of
differentiation, and completeness of excision of the carcinoma.
3.    The cancer is not poorly differentiated.
4.    There is no vascular or lymphatic involvement
5.    The margin of excision is not involved. Invasion of the stalk of a
pedunculated polyp, by itself, is not an unfavorable prognostic finding, as
long as the cancer does not extend to the margin of stalk resection.
Patients with malignant sessile polyps with favorable prognostic criteria
should have follow-up in about 3 months to check for residual abnormal
tissue at the polypectomy site. After one negative result examination, the
clinician can revert to standard surveillance as performed for patients with
benign adenomas.
When a patient's malignant polyp has poor prognostic features, the relative
risks of surgical resection should be weighed against the risk of death from
metastatic cancer. The patient at high risk for morbidity and mortality from
surgery probably should not have surgical resection. If a malignant polyp is
located in that part of the lower rectum that would require an
abdominal-perineal resection, local excision rather than a standard cancer
resection usually is justified. Rectal ultrasound studies may assist in
determining correct treatment. During colonoscopic excision of a large
sessile polyp that may require subsequent surgical resection, it may be
useful to mark the polypectomy site with India ink.
Primary Prevention of Colorectal Adenomas
To prevent initial or recurrent colorectal adenomas, a diet that is low in
fat and high in fruits, vegetables, and fiber is recommended. Normal body
weight should be maintained, and smoking and excessive alcohol use should be
avoided. Daily dietary supplementation with 3 g of calcium carbonate may
reduce the recurrence of adenomas. Other chemopreventive measures (i.e.,
supplementation with aspirin and other nonsteroidal anti-inflammatory drugs,
selenium, or folic acid), supported by indirect data, cannot yet be
recommended pending the results of ongoing clinical trials showing both
efficacy and a good risk-benefit ratio.
Surveillance of Families of Patients with Adenomas
Colonoscopic surveillance should be considered for first-degree relatives of
adenoma patients, particularly when the adenoma was advanced or diagnosed
before age 60 years, or, in the case of siblings, when a parent also had
colorectal cancer diagnosed at any age. When indicated, surveillance should
be initiated 5 years younger than the age of initial adenoma diagnosis, or
at age 40 years (whichever occurs first), and then at intervals of 3 to 5
years, depending on findings.
Postpolypectomy Surveillance
Complete colonoscopy should be done at the time of initial polypectomy to
detect and resect all synchronous adenomas. Additional clearing examinations
may be required after resection of a large sessile adenoma, or if (because
of multiple adenomas or other technical reasons) the colonoscopist is not
reasonably confident that all adenomas have been found and resected.
After a complete clearing colonoscopy has been accomplished after an initial
polypectomy, repeat colonoscopy to check for metachronous adenomas should be
performed in 3 years for patients at high risk for developing metachronous
advanced adenomas. This includes those who at baseline examination have
multiple (>2) adenomas, a large (>1 cm) adenoma, an adenoma with villous
histology or high-grade dysplasia, or have a family history of colorectal
cancer.
Repeat colonoscopy to check for metachronous adenomas should be performed in
5 years for most patients at low risk for developing advanced adenomas. This
includes those who at baseline examination have only one or two small
tubular adenomas (<1 cm) and no family history of colorectal cancer.
Selected patients at low risk for metachronous advanced adenomas may not
require follow-up surveillance.
After one negative follow-up surveillance colonoscopy, subsequent
surveillance intervals may be increased to 5 years. If complete colonoscopy
is not feasible, flexible sigmoidoscopy followed by a double-contrast barium
enema is an acceptable alternative. Follow-up surveillance should be
individualized according to the age and comorbidity of the patient, and
should be discontinued when it seems unlikely that follow-up is capable of
prolonging quality of life.
CLINICAL ALGORITHM(S):
None provided
DEVELOPER(S):
American College of Gastroenterology - Medical Specialty Society
COMMITTEE:
Practice Parameters Committee
GROUP COMPOSITION:
Author: John H. Bond, MD
ENDORSER(S):
American Society for Gastrointestinal Endoscopy (ASGE) - Medical Specialty
Society
American Gastroenterological Association - Medical Specialty Society


Edward E. Rylander, M.D.
Diplomat American Board of Family Practice.
Diplomat American Board of Palliative Medicine.