Colon Cancer Flashcards

(48 cards)

1
Q

T1

A

invades submucosa

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2
Q

T2

A

invades muscular propria

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3
Q

Tis

A

intramucosal cancer cells, does not breach muscular mucosal

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4
Q

T3

A

invades subserosa or into nonperitonealised pericolic or perirectal tissue

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5
Q

T4a

A

penetrates surface of visceral peritoneum

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6
Q

T4b

A

directly invades other organs

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7
Q

N1c

A

tumor deposits in the subserosa or non-peritonealized /perirectal soft tissue WITHOUT regional lymph node metastasis

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8
Q

Isolated tumor cells

A

20 cells within subcaosular or marginal sinus of lymph node

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9
Q

Micrometastases

A

cluster of 20 or more cells OR metastases measuring 0.2-2mm in diameter

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10
Q

N1a

A

1 regional lymph nodes

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11
Q

N1b

A

2-3 regional lymph nodes

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12
Q

N2a

A

4-6 regional lymph nodes

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13
Q

N2b

A

>7 regional lymph nodes

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14
Q

CEA

A
  • oncofetal antigen
  • first pass effect of liver
  • ~40-50% of CRC raised
  • Prognostic: >20 is poorer prognosis
  • Surveillance
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15
Q

Adenoma-carcinoma sequence

A

1) APC gene mutation
2) Activating K-ras oncogene
3) Inactivate p53 tumor suppressor gene

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16
Q

Molecular pathways for colorectal tumorigenesis

A

1) Chromosomal instability (APC) pathway
2) Mismatch repair pathway
3) Serrated /Hypermethylation phenotype (CIMP+) pathway

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17
Q

Chromosomal instability (APC) pathway

A
  • can be inherited (FAP) or sporadic
  • gross chromosomal abnormalities (deletions, insertions, loss of heterozygosity)
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18
Q

Oncogenes involved in sporadic CRC

A

RAS
SRC
MYC
HER2

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19
Q

RAS oncogene

A
  • point mutations
  • mutation restyle in continuous growth stimulation
  • 50% sporadic CRCs
  • 50% colonic adenoma > 1cm

3 subtypes HRAS, KRAS, NRAS

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20
Q

Tumor suppressor genes associated with CRC

A

APC
TP53
Chromosome 18q: DCC, SMAD4, SMAD2
TGF-beta signalling
BRCA1 and BRCA2

21
Q

Mismatch repair genes

A

-responsible for correcting nucleotide base mispairings/ small insertions/deltions during DNA replication

hMSH
hMLH1, 3
hPMS1,2
hMSH6

22
Q

KRAS

A
  • Encodes a small G protein on EGFR pathway
  • Wild type RAS = normal
23
Q

Colonoscopy documentation

A

Extent of examination
Photodocumentation of landmarks
Bowel prep quality
Location, size, morphology of lesions
Removal technique and completeness
Tattoo placement

24
Q

Metachronous tumor

A

Tumor detected more than 6 months after management of index tumor

25
SIGGAR trial 2013
lower detection rate AND miss rate of Barium enema compared to CTC
26
Pros and cons of PEG
Polyethylene glycol solution Pros: -minimal volumen shift -minimal electrolyte disturbance Cons: -requires compliance -risk of aspiration
27
Pros and cons of sodium phosphate agent
Pros: -small volume and quantity -better tolerance -better compliance Cons: -C/I in renal impairment due to phosphate content -risk of volume shift -risk of electrolyte disturbance
28
Rationale to forgo bowel prep before elective colonoic surgery
- most anastomotic leaks due to technical error and biological failure - Cochraine 2011 studies showed DID NOT reduce complication rate
29
When may bowel prep be considered in elective surgery
-proximal stoma planned (prevents stagnant stool remaining in left side of coon -easier bowel handling -facilitate on-table colonoscopy
30
Peri-operative blood transfusion in CRC surgery
- immunosuppressive - increase wound infection - increase intra-abdominal collection - increase recurrence (Cochrane Rev 2011)
31
TRIM
**Transfusion related immune modulation** immune suppression leading to tumor proliferation and invasion
32
Evidence for MDT approach
- reduce rate of positive CRM for rectal cancer - increase rates of adjuvant therapy for colon cancer - increases rates of metastasis surgery for patient ins stage 4 disease
33
Right hemicolectomy 1. Definition 2. Vascular supply 3. Indication (tumor location)
1. Removal of 10cm TI, AC HF and proximal 1/3 TC 2. ileocolic, right, right branch of middle colic 3. Cecal, AC cancer
34
Extended right hemicolectomy 1. Definition 2. Vascular supply 3. Indication (tumor location)
1. removal of 10cm TI, AC, TC, SF 2. ileocolic, right, middle +/- ascending branch of left colic 3. HF, proximal, mid transverse colon
35
Left hemicolectomy 1. Definition 2. Vascular supply 3. Indication (tumor location)
1. left colon 2. Ligation of IMA at origin 3. splenic flexure, descending colon, sigmoid colon
36
Extended left hemi-colectomy 1. Definition 2. Vascular supply 3. Indication (tumor location)
1. distal 1/3 of TC, colorectal junction 2. left branch of middle colic, IMA 3. splenic flexure tumor
37
CA splenic flexure. How to decide between extended right and left hemicolectomy?
1. Oncological clearance (anatomy of blood supply to splenic flexure and lymph nodes involved) 2. Technical aspect (tension free and good blood supply to anasomosis 3. Caecum and proximal colon viability
38
Surgical options for Splenic Flexure Cancer
Extended right hemicolectomy Extended left hemicolectomy Segmental splenic flexure resection
39
Segmental splenic flexure resection
left branch of middle colic and left colic vessels
40
Variation in supply of splenic flexure artery
89% by left colic 11% by SMA Missing middle colic 22%
41
5 year survival rate in colon cancer for each stage
Stage 1: 90% Stage 2: 70% Stage 3: 50% Stage 4: 10%
42
Left segmental colectomy ## Footnote 1. Definition 2. Vascular supply 3. Indication (tumor location)
1. Resection of descending colon 2. Left colic artery 3. Descending colon tumor
43
Indication for adjuvant chemotherapy in colon cancer
* Stage III * Stage II with high risk features *controversial, no definite evidence*
44
Evidence for addition of oxaliplatin to adjuvant chemotherapy in colon
MOSAIC NSABP C07 XELOXA
45
Adjuvant chemotherapy regimen for colon cancer
Oxaliplatin based regimen: * XELOX * FOLFOX * FLOX For 6 months after recovery from surgery
46
Complications of large bowel operation
* Early * Anastomotic leak * Accidental injury to other organs * Infection/ sepsis (wound, intra-abdominal) * Ileus * Late * Diarrhea * Impotence * Urinary incontinence * Adhesive I/O
47
High risk features in Stage II colon
* Poorly differentiated * Serosal involvement (T4) * Lymphovascular permeation * Margin involved * Extramural vascular invasion * Perineural invasion * Obstructed/perforated tumor * Fewer than 12 LN * Markedly elevated CEA
48
How to decide for adjuvant chemo in Stage II colon cancer?
Adjuvant! Online tool weights potential benefit with life expectancy, toxicity and risk