CRC, FAP, HNPCC Flashcards
Age of CRC
Peak in 60s
Role of adenomatous polyposis coli (APC) in colorectal cancer?
- APC is a protein that promotes degradation of β-catenin.
- Mutations in APC lead to increased β-catenin
= Increased cell proliferation
Sequence of events from formation of adenomas to colorectal carcinomas caused by APC mutation?
- First hit: mutation of one APC copy
- Second hit: mutation of second copy of APC (leads to adenoma formation)
- Further mutations (eg in KRAS and p53) in the adenoma –> malignant transformation
Risk factors for colorectal cancer?
- Diet: ↓ fibre + ↑ refined carbohydrate
- Inflammatory bowel disease
- Familial: FAP, HNPCC, Peut-Jeghers
- Smoking
- Genetic
Meds protective against CRC
Aspirin
NSAIDs
What type of carcinoma are the majority of colorectal cancers?
- 95% adenocarcinoma
- others: lymphoma, GIST, carcinoid
The 3 common sites for colorectal cancers?
Rectum: 35%
Sigmoid: 25%
Caecum and ascending colon: 20%
Symptoms of left sided colorectal cancer?
Left sided cancer:
- Altered bowel habit
- PR mass- Obstruction
- bleeding/ mucus
Sx of right sided CRC
anaemia
Anal fistula
a narrow tunnel with its internal opening in the anal canal and its external opening in the skin near the anus
MRI use for colorectal carcinoma?
MRI best for rectal Ca and liver mets
Tumour marker for CRC
CEA (carcinoembryonic Ag)
Staging of rectal tumour
Endoanal ultrasound
Findings of Ba enema in CRC
apple-core lesion
DUKES staging of colorectal cancer?
A. confined to bowel wall
B. through bowel wall but not lymph nodes
C. regional lymph nodes
D. distant mets
T in TNM staging of colorectal cancer?
TIS: carcinoma in situ
T1: submucosa
T2: muscularis propria
T3: subserosa
T4: through the serosa to adjacent organs
N in TNM staging of CRC
N1: 1-3 nodes
N2: >4 nodes
Grading of colorectal cancer?
Grading from low to high
- Based on cell morphology
- Dysplasia, mitotic index, hyperchromatism
Pre-operative preparation for colorectal cancer resection surgery?
Kleen Prep (Macrogol: osmotic laxative) the day before
Phosphate enema in the morning of surgery.
Discuss stomas (Stoma nurse consult for siting)
Surgical options for rectal cancer management?
- Anterior resection:
- Abdominoperineal resection
- Total mesorectal excision (TME)