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.