neoplastic disease of the GI tract part 3 W8

Question 1

colorectal polyps types?

Answer 1

inflammatory (IBD, lymphoid)
hamartomatous (mixture of cell types in abnormal proportion)
hyperplastic (common)
lesions in submucosa eg lipoma presenting as a polyp

Question 2

neoplastic polyps?

Answer 2

adenomas (benign. tubular/tubulovillous/villous)
adenocarcinomas

Question 3

more villous adenomas mean what?

Answer 3

more likely to progress to malignancy

Question 4

where do colorectal carcinomas typically metastasise to?

Answer 4

the liver

Question 5

colorectal adenocarcinoma mainly occur where?

Answer 5

rectum/sigmoid 55%
caecum/ascending colon 22%

Question 6

dietary risk factors for colorectal adenocarcinoma?

Answer 6

excess calorie intake
low fibre
high refined carbohydrates
high red meat intake
low intake of protective macronutrients - vit A/C/D/E

Question 7

other risk factors for colorectal adenocarcinoma?

Answer 7

first degree relative with CRC
inherited syndromes
alcohol in rectal carcinomas
smoking
IBD
radiation
occupational factors eg solvents
schistosomiasis (parasitic infection)

Question 8

colorectal carcinoma genetic features?

Answer 8

APC/beta-catenin pathway (inactivation of APC tumour suppression gene). early stage mutation.

microsatellite instability pathway (inactivation of DNA mismatch repair genes). less common.

“serrated neoplasia” pathway (distinctive precursor lesions showing similarities to hyperplastic polyps).

Question 9

colorectal carcinoma - prognostic factors?

Answer 9

stage: higher = reduced survival
grade: poorly differentiated tumours more aggressive
presentation with obstruction or perforation
involvement of surgical resection margins
extramural vascular invasion
patterns of invasion and host response
genetic markers