Colon Cancer Flashcards
(48 cards)
T1
invades submucosa
T2
invades muscular propria
Tis
intramucosal cancer cells, does not breach muscular mucosal
T3
invades subserosa or into nonperitonealised pericolic or perirectal tissue
T4a
penetrates surface of visceral peritoneum
T4b
directly invades other organs
N1c
tumor deposits in the subserosa or non-peritonealized /perirectal soft tissue WITHOUT regional lymph node metastasis
Isolated tumor cells
20 cells within subcaosular or marginal sinus of lymph node
Micrometastases
cluster of 20 or more cells OR metastases measuring 0.2-2mm in diameter
N1a
1 regional lymph nodes
N1b
2-3 regional lymph nodes
N2a
4-6 regional lymph nodes
N2b
>7 regional lymph nodes
CEA
- oncofetal antigen
- first pass effect of liver
- ~40-50% of CRC raised
- Prognostic: >20 is poorer prognosis
- Surveillance
Adenoma-carcinoma sequence
1) APC gene mutation
2) Activating K-ras oncogene
3) Inactivate p53 tumor suppressor gene
Molecular pathways for colorectal tumorigenesis
1) Chromosomal instability (APC) pathway
2) Mismatch repair pathway
3) Serrated /Hypermethylation phenotype (CIMP+) pathway
Chromosomal instability (APC) pathway
- can be inherited (FAP) or sporadic
- gross chromosomal abnormalities (deletions, insertions, loss of heterozygosity)
Oncogenes involved in sporadic CRC
RAS
SRC
MYC
HER2
RAS oncogene
- point mutations
- mutation restyle in continuous growth stimulation
- 50% sporadic CRCs
- 50% colonic adenoma > 1cm
3 subtypes HRAS, KRAS, NRAS
Tumor suppressor genes associated with CRC
APC
TP53
Chromosome 18q: DCC, SMAD4, SMAD2
TGF-beta signalling
BRCA1 and BRCA2
Mismatch repair genes
-responsible for correcting nucleotide base mispairings/ small insertions/deltions during DNA replication
hMSH
hMLH1, 3
hPMS1,2
hMSH6
KRAS
- Encodes a small G protein on EGFR pathway
- Wild type RAS = normal
Colonoscopy documentation
Extent of examination
Photodocumentation of landmarks
Bowel prep quality
Location, size, morphology of lesions
Removal technique and completeness
Tattoo placement
Metachronous tumor
Tumor detected more than 6 months after management of index tumor