Cancer as a disease -colorectal cancer : part 2

Question 1

Recall the 5 categories of adenoma, how can they be categories

Answer 1

Tubular Tubulovillous Villous(like villi) Pedunculated (on a stalk) Sessile (rug-on-carpet)(you can be the either one of the last two and the first three at same time)

Question 2

Recall a complication of specifically villous polyps

Answer 2

Rarely Can become hyper-secretory to induce a hypokalaemia

Question 3

What mutation gives rise to APC

Answer 3

5q21 deletion

Question 4

What are microsatellites? What causes microsatellite instability?

Answer 4

Mismatch-repair gene mutation(Recessive genes requiring 2 hits.)

Microsatellites are repeat sequences prone to misalignment. Some microsatellites are in coding sequences of genes which inhibit growth or apoptosis e.g.TGFbR11

Question 5

What is the functional consequence of having a microsatellite instability?

Answer 5

Cannot repair faulty DNA

Question 6

Descirbe the cellular structure of tubular and villous polyps

Answer 6

Tubular = Columnar cells with nuclear enlargement, elongation, multilayering and loss of polarity

Villous = Mucinous cells with nuclear enlargement, elongation, multilayering and loss of polarity,Exophytic, frond-like extensions

Question 7

About what % of cancer-related deaths are attributable to colorectal cancer?

Answer 7

10%

Question 8

What features of diet can protect against colorectal cancer

Answer 8

Folate (Co enzyme for nucleotide synthesis and DNA methylation)Vit C and E

Question 9

Where in the colon are colorectal tumours mostly found?

Answer 9

Recto-sigmoid

Question 10

Recall 3 factors that may indicate high-risk screening for colorectal cancer

Answer 10

1. Implicated gene mutation 2. Crohn’s 3. UC

Question 11

If the screening test is positive for colorectal cancer, what additional testing is carried out?

Answer 11

Endoscopy - looking for polyps

Question 12

WHat is the usual length of time between adenoma development and a colorectal malignancy developing?

Answer 12

15 years

Question 13

What grading system is used for colorectal cancer?

Answer 13

Duke’s

Question 14

What do inflammatory markers indicate about a colorectal cancer?

Answer 14

Good prognosis

Question 15

Describe the features of a hyperplastic polyps

Answer 15

Very common

<0.5 cm

90% of all LI polyps

Often multiple

No malignant potential

15% have k-ras mutation

S

Question 16

HOw is mucin affected in colon cancer

Answer 16

Still being produced but increased and in te wrong places