You could be asked how to handle colon polyps by many different scenarios. Most of them start by, "the gastroenterologist called you after a colonoscopy and polypectomy and informed you that..." What would you do? This is certainly a common encounter during clinical practice and even more common on the Board. To start, let us take a moment to classify colon polyps:
1. Hyperplastic (small, usually <5mm, benign with no malignant potentials).
2. Hamartomas (these include juvenile polyps and polyps in Peutz-Jeger syndrome; they are benign with some malignant potentials in the GI tract and elsewhere in the case of PJS).
3. Neoplastic (these include tubular adenomatous, villous and mixed tubulo-villous Polyps and polypoid CA of the colon. The more villous or atypia component they have, the more risk of developing CA).
4. Others (include lymphoid polyps, hemangiomas, lipomas, inflammatory polyp).
Hyperplastic and hamartoma polyps need no specific treatment except for endoscopic removal in the safest way possible if they are found incidentally or they are associated with complications like bleeding, intussusception... etc.
Most questions center around neoplastic polyps and I am going to go through all imaginable scenarios.
One rule to remember, any polyp bigger than 2 cm carriers higher than 35% chance of cancer risk if it is a tubular adenoma and higher than 50% chance of cancer if it is villous adenoma.
A. After polypectomy, CA in situ was found in the specimen => polypectomy is enough. Continue close follow-up with colonoscopy.
B. The polyp has CA invading the muscularis mucosa (not the muscularis propria) => If the resection has clear margins of at least 2 mm, the cancer is well differentiate, has no angio or lymphatic invasion, and the patient has no evidence of lymph nodes enlargement in preop study, it is safe to proceed with close follow up with frequent colonoscopies in such a patient. If any of the criteria mentioned above is not met, the patient should have a cancer operation.
Normally the answer to this scenario was that the patient should undergo cancer operation for the 5-20% incidence of positive lymph nodes in this situation. This is still a safe answer, but you should know that recent studies have demonstrated the following:
In polyps with CA invading the muscularis mucosa, but the CA is well differentiated and the polyp's stalk is free of tumor for at least 0.5cm, and there is no venous or lymphatic invasion, close follow-up with colonoscopy is acceptable for the extremely low incidence with these circumstances of positive L.N. (this applies only to polypoid lesions with a stalk, not sessile polyps).
C. The polyp's stalk is involved with CA => the patient needs cancer operation.
D. The polyp is sessile, cannot be removed safely by colonoscopy, a biopsy showed villous adenoma =>
The polyp is above 7cm from the anal verge => laparoscopic or open segmental colon resection.
The polyp is below 7cm from the anal verge => transrectal local resection. These villous adenomas are treated in the same manner even if they harbored CA in situ, but if the CA crosses the basement membrane, the patient needs a cancer operation (abdominoperineal resection).
*After colonoscopy in a young patient, a large number of polyps (>10) was found in the entire colon. The family history is positive for familial polyposis; what would you do?
About familial polyposis you have to know the following facts:
There are two syndromes involved here :
Familial adenomatous polyposis (FAP) represent 1% of colon CA cases:
Autosomal dominant, 100% potential for malignancy, polyps starts at puberty, most of them need prophylactic total colectomy at the age 20, always check for duodenal polyps associated with this syndrome.
Treatment: Proctocolectomy, rectal mucosectomy, and ileoanal pouch (j-pouch) with lifetime surveillance for residual rectal mucosa. Gardner syndrome is a variety of familial adenomatous polyposis and is associated with gastric and duodenal polyps and desmoid tumor in scars and in small intestine and osteoma especially in the mandible.
Hereditary Nonpolyposis Colon Cancer (HNPCC ) 5% of colon CA cases:
Autosomal dominant, associated with DNA mismatch repair gene, predilection for right sided and multiple cancer, some are associated with ovarian and endometrial or bladder cancer, needs surveillance colonoscopy starting at the age 25 and women need endometrial biopsy every 3 years.
Treatment: Consider subtotal colectomy with first cancer operation.
Some of the surgical procedures performed on these patients include the following:
Proctocolectomy + Brooke ileostomy (excellent results; may be the only choice in obese patients or patients with invasive CA in the rectum or patients with desmoids tumors or gastroduodenal polyps. Of course, it has some psychological problems).
Proctocolectomy + Koch's pouch (sounds attractive, but has high incidence of complications. Pouch leak, volvulus, Pouchitis, etc.).
Subtotal colectomy + ileorectal anastomosis + frequent polypectomies to rectal polyps ( The major disadvantage is the risk of developing invasive CA in the rectal stump, but this procedure has the least incidence of impotence or retrograde ejaculation in men).
Proctocolectomy + rectal mucosectomy + pull through ileoanal anastomosis, this is now the procedure of choice. It is a two stage procedure that involves the following:
Total abdominal colectomy, staying close to the bowel wall during dissection to avoid ejaculatory problems in males post-op. The rectal dissection is continued to a distance of 4-5cm from the dentate line, then the rectum is transected with a GA stapler. The ileum then is mobilized as much as possible by incising the mesentery away from the marginal arterial arches, all the way to the root of the mesentery. The rectal mucosectomy then is done through a dilated anus by everting the rectal stump, injecting some diluted epinephrine in the submucosa and carrying out the mucosectomy with a Bovie from the dentate line upward leaving basically a 4-5cm muscular cuff. Then a J pouch is created by folding an 18cm segment of the distal ileum on itself, making a 3cm enterotomy at the J apex and introducing a long GIA through the rectal muscular cuff to the anus and 3-0 Vicryl interrupted sutures are used to anastomose the enterotomy at the apex of the J pouch to the anus at the dentate line.
Finally, a segment of small bowel approximately 15cm proximal to the J pouch is chosen and a loop ileostomy is created and brought through a separate small abdominal incision. The distal limb is stapled and the proximal limb is matured as totally diverting ileostomy. Drains are placed in the pelvis and perineum and the abdomen is closed. Post-operatively, the patient is placed on Flagyl + Lomotil + psyllium and followed closely for 8 weeks.
After 8 weeks, a "pouchogram" is performed. If this shows no leak and the patient is generally doing well, he/she is scheduled for the second stage operation, which is basically the closure of the ileostomy, usually done 3 months after the first operation. The reported results of the operation are favorable. Sexual disorder (mainly retrograde ejaculation in men) complications incidence is about 10%.
Most patients will have about 6-10 loose bowel movements during the day and 2-3 during the night with soilage, but these numbers improve significantly over 6-12 months with most patients (about 80%) having no soilage or night bowel movements. Other complications include: anal stenosis (can be dilated), pouch leak (decreased significantly with protective ileostomy and Flagyl), acute Pouchitis is seen mostly as a sudden increase in the number of bowel movements and is treated, again, with oral Flagyl after ruling out anastomotic stenosis by proctoscopy.
The reason I went into so much details in this operation is that it has been asked frequently on the Board exam, and you are expected to know it whether you do this operation in your practice or not.
Finally, a couple of words about Hamartomatous polyps (for recert. exam):
* Juvenile Polyps are benign Hamartomas seen in children.
* Peutz- Jegher's Syndrome in autosomal dominant inherited and is associated with melanin spots on lips and oral mucosa and Hamartomatous polyps in both the small and large bowel and elsewhere.
* Cronkhite-Canada Syndrome (Hamartomatous GI polyps, alopecia, pigmentations, nail atrophy, diarrhea, vomiting and protein loss).
* Cowden's syndrome (Hamartomatous oral papules and GI polyps with predisposition to other cancers).