Colon Cancer Questions

Q1. Risk of Colon Cancer in Adenomatous polyp is related to all except

a) Size

b) Number

c) Histological appearance

d) Dysplasia

Q2. Colon polyps are generally managed endoscopically. Which of the following is not an indication for resectional surgery

a) Lymphovascular invasion

b) Poor differentiation

c) Flat or ulcerated lesion

d) Lesion in upper 1/3rd of submucosa

Q3. Which of the following organs are not involved in Familial Adenomatous Polyposis

a) Adrenals

b) Thyroid

c) Astrocytomas

d) Hepatoblastomas

Q4. What is not true for HNPCC

a) It is the most common hereditary colorectal cancer syndrome in USA

b) It is associated with MMR gene mutation

c) It is associated with APC mutation

d) It is associated with carcinoma colon and extraintestinal cancers

Q5. Which of the following is not fermented by colonic bacteria

a) Lignin

b) Pectin

c) Cellulose

Q6. True about Ulcerative Colitis with malignancy

a) It has a better prognosis

b) Is related to disease activity

c) Is related to duration of ulcerative colitis

d) Malignancy is more in anorectal ulcerative colitis

Q7. In ulcerative coilitis with toxic megacolon lowest rate of recurrence is seen in

a) Complete proctocolectomy and Brook's ileostomy

b) Ileo rectal anastomoses

c) kock's pouch

d) Ileo anal pull through procedure

Q8) All are precancerous for colon cancer

a. Crohn's disease

b. Bile acids

c. Fats

d. Carotene

Answers

1.b

Most colon cancer arise from adenomatous polyps over an interval of 8-10 years. The risk of cancer is related to the type of polyp ( if it is tubular, villous or tubulovillous), size ie more than 2 cm and the severity of dysplasia.

Cumulative risk of colon cancer developing at the site of poylp is 2.5% at 5 years, 8% at 10 years

Schakelford 6th edition page 2153

2. d

Malignant poylp is one in which the colon cancer has spread beyond muscularis mucosa into lamina propria or muscularis mucosae. Colonscopic polypectomy maybe done in favourable polyps

The indications for colectomy are

a) Poor differentiation

b) Lympho vascular invasion

c) Flat or Ulcerated Lesion

d) Invasion in lower 1/3rd of submucosa and not upper 1/3rd

e) Cancer with in 2 mm of resected polyp

Schakelford 6th edition page 2156

3. c

Familial Adenomatous Polyposis (FAP) is associated with cancer of colon and rectum

Rare tumors associated with it are

Medulloblastomas

Glioma

Liver

Adrenal

Thyroid

Sabiston 17th page 1452

4. c

HNPCC is associated with mutations of MMR (Mismatch Repair) genes and not APC gene which is mutated in FAP

Sabistion 17th 1453

5. a

Lignin is a non carbohydrate component of plants which is not fermented by colonic bacteria. It attracts water producing bulk.

Lignin is used to treat constipation

Cellulose is partly fermented

Pectin is completely fermented and used to treat diarrhea.

6 .c

Colon Cancer afflicts patients with ulcerative colitis 7 to 30 times more frequently than it does the general population.

The risk of colon cancer in ulcerative colitis is related to two factors:

(1) duration of the colitis, and

(2) extent of colonic involvement.

The risk of colon cancer for patients who have had the disease less than 10 years is low, but this risk steadily increases. The cancer risk for patients who have had disease activity for 10 to 20 years is 23 times that of the general population, while a disease duration of more than 20 years is associated with a cancer risk 32 times greater than that of the general population. The extent of colonic involvement in colitis also influences the risk of cancer. The incidence of cancer when ulcerative colitis is limited to the rectum or to the left side of the colon is much lower than when ulcerative colitis involves the entire colon.

The coloni cancer associated with ulcerative colitis is generally an adenocarcinoma evenly scattered throughout the colon. The adenocarcinoma is often flatter than cancers in the general population and has fewer overhanging margins. It is generally considered extremely aggressive.

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7. a

Total proctocolectomy with brooke's ileostomy removes almost all of the diseased segment.

IRA and IPAA leave behind rectal mucosa which may or may not be diseased

8) d

Carotene, Vit C and Calcium reduce the risk of colon cancer