Flashcards in Tumors of the bowel Deck (68)
What is the lifetime risk of colorectal cancer?
However, the incidence is declining
How much time does it take for a benign adenoma to become a colon cancer?
How common is CRC?
3rd most common form of cancer in men and women. 3rd leading cause of cancer death in US
What are the intrinsic risk factors of colorectal cancer?
What are the controllable risk factors in colorectal cancer?
1. Caloric intake/obesity
2. Red meat consumption
3. Alcohol consumption
Where are most colorectal cancers found?
Distal to the splenic flexure of the colon
What genetic factors increase your risk of CRC?
1. History of colorectal neoplasia
3. HNPCC mutation
Most cases of CRC occur after the age of:
If you meet someone who has CRC under the age of 50...what are you worried about?
How is FAP inherited? What gene is mutated?
Autosomal dominant disorder
-Mutated APC gene
What is peutz-jeghers syndrome?
Autosomal dominant disorder
-Multiple hamartomatous polyps of the entire GI tract
-melanosis of lips and buccal mucosa
Are PJ polyps malignant?
No, but these patients have a higher incidence of carcinoma elsewhere in the colon (breast, pancreas, ovary, uterus, lung)
How and when should you treat FAP?
Cancer develops early (late 30's). Treat early on with a total colectomy, before the age of 25
What are the carcinogens identified in colorectal cancer?
1. Fecal bile acids
2. Heterocyclic amines
3. Fecapentenes (anaerobic breakdown of fatty acids)
4. 3-ketosteroids (oxidation product of cholesterol)
What are some protective measures for colorectal cancer?
Does the two-hit hypothesis apply to CRC?
Yes. Molecular pathways to sporadic and inherited cancers are the same
How is familial colorectal cancer inherited?
We don't understand this. Family hx plays a role but this isn't a typical inherited syndrome
Do you have to have a family history of FAP to get FAP?
No. 25% have a spontaneous germline mutation
How do you diagnose FAp?
>100 polyps in the colon and rectum
What is the most common cause of death in FAP?
How is MYH polyposis inherited?
Which gene is mutated in MYH polyposis?
mutY homolog gene, which does base excision repair for oxidative DNA damage
What does MYH polyposis look like when you do endoscopy?
usually 15-100 adenomas. Early (age 45) CRC
Where do MYH polyposis cancers occur?
In the ascending colon. Important to consider if early polyps and many polyps but no APC gene abnormality
What is the most common inherited colon cancer syndrome?
Hereditary Non-Polyposis Colon Cancer (HNPCC)
How is HNPCC inherited?
Where is the mutation in HNPCC?
Mismatch repair genes (MMR)
How do you diagnose HNPCC?
Clinically indistinguishable from sporadic CRC (only one poly developing into CRC) Can only diagnose through personal and family history
What are the two types of HNPCC (lynch syndrome)
Lynch syndrome 1: CRC only
Lynch syndrome 2: CRC + endometrial and other cancers)