FN: Colorectal Carcinoma: Pathology and Presentation Flashcards
1
Q
Epi
A
3rd commonest cancer 2nd commonest cause of cancer deaths (16,000/yr) Age: peak in 60s Sex: rectal Ca commoner in men Geo: western disease
2
Q
Colonic adenomas
A
Benign precursos to CRC
Characterised by dysplastic epithelium
3
Q
Classificatino of colonic adenomas
A
Tubular
Villous
Tubulovillous
4
Q
Tubular
A
Small, pedunculated, tubular glands
5
Q
Villous
A
Large
Sessile
Covered by villi
6
Q
Tubulovillous
A
Mixture
7
Q
Colonic adenomas presentation
A
Typically asymptomatic
Large polyps can bleed - IDA
Villous adenomas can - reduced potassium + hypoproteinaemia
8
Q
Colonic aenomas malignant potential
A
increased size
Increased dysplasia
Increased villous component
9
Q
APC et al:
A
- -ve regulator of Beta-catenin (component of WNT pathway)
- APC binds to and promotes degradation of Beta-catenin
- APC mutation - rise in Beta-catenin and rise in transcription of genes which promote cell proliferation
- Proliferation - mutation of other genes which promote growth and prevent apoptosis
- KRAS (proto-oncogene)
- p53 (TSG)
10
Q
Adenoma - Carcinoma Seqeunce
A
- First hit: mutation of one APC copy
- Seconda hit: mutation of second of APC copy –> adenoma formation
- Additional mutations in adenoma - malignant transformation e.g. KRAS, p53
11
Q
Other aetiological Factors
A
- Diet: reduced fibre + raised refined carbohydrate
- IND: CRC in 15% with pancolitis for 20 yrs
- Familial: FAP, HNPCC, Peutz-jeghers
- Smoking
- genetics:
- no relaticeL1/50 CRC risk
- One 1st degree: 1/10 - NSAIDS/Aspirin (300mg/d): protective
12
Q
Pathology GI malignancy types
A
95% adenocarcinoma
Others: Lymphoma, GIST, carcinoid
13
Q
Location
A
Rectum:35% Sigmoid:25% Caecum and ascending colon:20% Transverse:10% Descending:5%
14
Q
Proximal tumours
A
sessile or polypod
15
Q
Distal tumours
A
Annular stenosing
