colon cancers from pathoma

Question 1

What are the pathways by which colorectal carcinomas arise?

Answer 1

adenoma-carcinoma sequence (most common) or microsatellite instability pathway

Question 2

What is the microsatellite instability pathway?

Answer 2

microsatellites are repeating sequences of non-coding DNA. everytime we have cell division, we copy the microsatellites are copied too. if the patient has a problem with DNA mismatch repair, they will have microsatellite INSTABILITY. other genes, too, are unstable. mutations in other genes can cause the development of a colorectal carcinoma

Question 3

HNPCC

Answer 3

hereditary nonpolyposis (tumors arise de novo- no adenoma first) colorectal carcinoma.
they have incr. risk of colorectal, ovarian, and endometrial carcinoma.  often arises de novo at an early age, often right sided.

Question 4

how does left sided cancer usually present?

Answer 4

decr. stool caliber, LLQ pain, and blood streaked stool. it is squeezing down on the lumen. adenoma carcinoma sequence very common

Question 5

how does right sided cancer usually present

Answer 5

tends to grow as a raised lesion. may cause iron deficiency anemia (the colon lumen is bigger). key location for HNPCC lesions.

Question 6

What is the tumor marker for colon cancer?

Answer 6

CEA. useful for assessing tx response and detecting recurrence. not good for screening.

Question 7

key finding on X ray for colorectal cancer

Answer 7

apple core lesion