Colorectal Carcinoma - Pathoma

Question 1

What are the two major molecular pathways in which colorectal cancer may arise?

Answer 1

• Adenoma-Carcinoma Sequence
  
  • APC, KRAS, p53/COX
  • most common (80%)
• Microsatellite instability (MSI)
  
  • problems with DNA replication of repeated sequences on non-coding DNA

Question 2

What major Colorectal Cancer arises due to the Microsatellite Instability pathway?

Answer 2

• Hereditary Non-Polyposis Colorectal Carcinoma (HNPCC)
  
  • inherited mutation in DNA mismatch repair enzymes
  • no polyps, carcinoma arise de novo at a relatively early age

Question 3

Patients with HNPCC are at an increased risk for what 3 types of cancer?

Answer 3

• Colorectal Carcinoma
• Ovarian Carcinoma
• Endometrial Carcinoma

Question 4

Patients with what two colon pathologies are also at high risk for Colorectal Carcinoma?

Answer 4

• Patients with:
  
  • Ulcerative Colitis (chronic inflammation)
  • Peutz-Jeghers

Question 5

How does left-sided Colorectal Carcinoma usually grow/present?

Answer 5

• Grows as “napkin ring” lesion
  
  • grows circumferentially
• Decreased stool caliber
  
  • pencil-thin stools
• Left lower quadrant pain
• Blood-streaked stool
• ***More commonly originates through the Adenoma-Carcinoma Sequence

Question 6

How does right-sided Colorectal Carcinoma usually grow/present?

Answer 6

• Grows as a raised lesion
• Presents as:
  
  • Iron deficiency anemia
  • Vague pain
  • constipation

Question 7

Why do patient’s with Colorectal Carcinoma have an increased risk for Streptococcus bovis endocarditis?

Answer 7

No idea!

(pathoma said it was important)

Question 8

What is an important tumor marker in Colorectal Carcinoma? What is it used for?

Answer 8

• CEA = serum tumor marker
  
  • useful for assessing treatment response and detecting recurrence
  • Not usefor for screening