Colorectal Cancer Flashcards
What are the histological layers of the GI tract from the inside out?
- Mucosa
- Submucosa
- Muscularis propria
- Subserosa
- Serosa - adventitia, peritoneum
What type of cancer are the vast majority of colorectal cancers and how common is it in the UK?
- Adenocarcinoma
2. 3rd most common cancer in the UK
In which age group is colorectal cancer usually found?
Uncommon <40, 86% in those >60.
What is significant in the history of someone presenting with colorectal cancer?
- FHx of colorectal cancer
- PMHx of colorectal cancer, previous polyps >1cm with high grade dysplasia
- Long standing - Crohn’s and ulcerative colitis, DM, immunosuppression, radiation exposure to the abdomen.
- Smoking, obesity, processed red meat, low fibre, alcohol.
What is the defect in Lynch syndrome and what is the inheritance pattern?
- Microsatellite instability - germline mutation in DNA mismatch repair genes (80% lifetime risk of colorectal cancer)
- Autosomal dominant (3% of colorectal cancers)
Which cancers does Lynch syndrome predispose to?
Endometrial (most common in women), ovarian, and GIT cancers (colorectal most common in men).
What is the surveillance for people with Lynch syndrome?
Colonoscopic surveillance at least every other year from 25 years old.
Where does Lynch syndrome colorectal cancer arise in the colon and how well differentiated are the cells?
- Right side of colon
2. Moor poorly differentiated
What is familial adenomatous polyposis?
Hundreds of adenomatous polyps develop in the colon during the 2nd to 3rd decade of life.
At what age is adenocarcinoma development inevitable in familial adenomatous polyposis?
35 years
What is the defect in familial adenomatous polyposis and what is the inheritance pattern?
- Germline mutation in APC gene (tumour suppressor)
2. Autosomal dominant
What is the surveillance and management for familial adenomatous polyposis?
- Surveillance sigmoidoscopy from 12 years
2. Prophylactic total bowel removal (panproctocolectomy) <25 years
Which cancers is familial adenomatous polyposis most associated with?
Small bowel, gastric, and thyroid cancers
What are the two main inherited disorders which increase your risk of developing colorectal cancer?
- Lynch syndrome
2. Familial adenomatous polyposis
What is the main protective factor for colorectal cancer?
- Vegetarian and high fibre diet
2. Daily aspirin use