colon cancers from pathoma Flashcards
What are the pathways by which colorectal carcinomas arise?
adenoma-carcinoma sequence (most common) or microsatellite instability pathway
What is the microsatellite instability pathway?
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
HNPCC
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.
how does left sided cancer usually present?
decr. stool caliber, LLQ pain, and blood streaked stool. it is squeezing down on the lumen. adenoma carcinoma sequence very common
how does right sided cancer usually present
tends to grow as a raised lesion. may cause iron deficiency anemia (the colon lumen is bigger). key location for HNPCC lesions.
What is the tumor marker for colon cancer?
CEA. useful for assessing tx response and detecting recurrence. not good for screening.
key finding on X ray for colorectal cancer
apple core lesion