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05-30-2008, 09:31 AM
m Incidence:
· Age: 50 - 60 years but young patient may also involved.
· Site: The commonest site affected is pelvic colon.
· Sex: Male > Female in CA Lt. colon but Female > Male in Rt. side.
mPathology:
· Sites: Sigmoid colon 70% & Caecum 12%
· Precancerous lesions:
1- Adenomatous polyp. 2- Villous papilloma. 3- Familial polyposis. 4- Gardner's syndrome. 5- Ulcerative colitis.
Recently, Molecular biology studies explain the influence of diet and other factors on genetic oncogenic base. Many genes are described to be involved in the start and progression of colonic carcinoma e.g. Adenomatous polyposis coli gene (APC gene), DNA hypomethylation gene, DCC, FCC, P53, K-ras and others.
Therefore colonic neoplasms constitute an ideal system for studying the genetic alterations responsible for tumour initiation and progression.
· Macroscopic picture:
1- Cauliflower = Fungating = proliferating:
* Site: capacious area (Ascending colon)
* Growth: inside > outside
* Differentiation: Well differentiated = low grade of malignancy.

2- Infiltrating = Annular:
* Site: narrow area (Lt. colon, rectosigmoid junction)
* Growth: outside > inside.
* Differentiation: Poor differentiation. = High grade of malignancy
3- Ulcerative:
* Site: caecum. *Growth: inside = outside
* Differentiation: Moderate " intermediate grade of malignancy".
* Criteria of malignant ulcer: Raised everted edge,necrotic floor and indurated base.
· Microscoopic picture:
a) Adenocarcinoma of different grades of differentiation.
- Differentiated Columnar cells and acinar cells.
-Undifferentiated * schirrous: more fibrous element.
* encephaloid. less fibrous element.
* anaplastic: more marked increase in cellular element.
b) Mucoid carcinoma (signet ring apperance), very bad prognosis.
· Spread:
1- Direct ® to the wall of the colon in circular manner.
® to surroundings small intestine stomach pancreas, psoas muscle.
2- Lymphatic: Epicolic, paracolic, intermediate ® Main group (sup. & inf. mesentric L.N.)
3- Blood spread: mainly to the liver
· Investigations:
1- P.R. examination: Mass in rectosigmoid junction may be felt.
2- Sigmoidoscope or fiberoptic colonoscope:
can be used up to iliocecal valve and take biopsy.
3- Barium enema: a- Annular type:Narrowing (stricture)in Lt colon.
b- Fungating type: Filling defect. (Rt side).
c- Ulcerative type: Filling defect in caecum.
4- Double contrast enema:
Barium enema, then evacuate it, then air introduced into the colon. It is used to detect small lesions.
5- Carcino-embryonic antigen (CEA): It is a tumour marker for colorectal cancer. It is of value to follow up patients after surgery to detect recurrence.
· Treatment of Cancer Colon:
I) Preoperative Treatment:
"When there is no intestinal obstruction"
1- Blood transfusion to correct anaemia.
2- High caloric low residure diet.
3- Mechanical and chemical preparation of the colon.
a) Mechanical preparation:
* Slow: Along 3days of enema twice daily.
* Rapid: Whole gut irrigation with saline through nasogastric tube at a rate of 2-4 litres/hour for 3-4 hours.
* On table: lavage may be necessary in some obstructed cases when primary resection is decided.
b) Chemical preparation:
* Flagyl tablets 1 x 3 for colonic anaerabic infection.
* Neomycin tablets poorly absorbed from intestine so it acts locally.
* New cephalosporins I.V. 1gm/12hs. is also effective for rapid preparation.
II) Operative Treatment:
When intestinal obstruction is present preliminary drainage of the intestine proximal to obstruction must be performed.
Right side rarely need such precautions. But left sided obstruction usually treated in such way unless an exprerienced surgeon decides that immediate resection is safe.


Operations for Operable Cases
m Cancer Caecum ®Rt. hemicolectomy in which we remove the distribution of ileocolic and right colic arteries with intermediate groups of L.N. Ended by ileo transverse colostomy. The terminal 10 cm of ileum, the right colon and right 1/3 of transverse colon is removed and ileotransvers colostomy is done.
m Cancer hepatic flexure ® Resection extended correspondingly to involve the middle colic distribution. "extended Rt. hemicolectomy". The transverse colon and splenic flexure is added to the right hemicolectomy.
m Cancer transverse colon ® Transverse colon with both flexure and omentum of them are removed. Rt-Lt colocolic anastomosis is done.
m Cancer of the pelvic colon ® Left hemicolectomy in which we remove the distribution of inferior mesenteric artery with its main group of lymph nodes. We remove sigmoid and ascending colon with splenic flexure. Ended by coloproctostomy.
m Cancer of splenic flexure or descending colon ® Extension of the left hemicolectomy to involve the whole transverse colon and the hepatic flexure is needed. Excision of the whole ascending colon may facilitate ileorectal anastomosis.


For Inoperable Cases
Proximal bypass is needed for obstructed cases e.g. iliotransverse colostomy in the right side or proximal colostomy in the left side.
Chemotherapy and morphia are also needed.
III) Post operative care:
Antibiotics should be given to guard against possible infection of the anastomotic area. Free fluids are not given by mouth after anastomotic operations until flatus is passed.
A Which is more worse prognosis CA Lt colon or Rt colon?
Both has the same prognosis approximately why?
- Lt side is of high grade of malignancy and the spread is rapid due to abscence of one lymph node station. But, it presents early and main group of L.N. can be excised. "inferior mesenteric artery can be ligated.
- Rt side is of low grade malignancy and lymphatic spread is slower. But, it presents late and less radical resection can be done.



A Why we cann't do 1ry resection anastomosis of the colon without preparation [as small intestine]?
Due to:1- High bacterial content.
2- Constant gas distension.
3- Incomplete serous covering.
4- Low vascularity makes ischaemia at suture line is more than small intestine.

SOURCE: DR. AYMAN SALEM'S BOOK
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