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MS3 - GI > Colorectal carcinoma, FAP, HNPCC, Peutz-Jeghers, GI polyps > Flashcards

Colorectal carcinoma, FAP, HNPCC, Peutz-Jeghers, GI polyps Flashcards

1
Q

Epidemiology of colorectal carcinoma

Age? Sex? Geography?

A

Peak in 60s,
More in men
Western disease

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2
Q

Role of adenomatous polyposis coli (APC) in colorectal cancer?

A
  • APC is a protein that promotes degradation of β-catenin.

- mutations in APC lead to increased β-catenin, and increased cell proliferation

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3
Q

Sequence of events from formation of adenomas to colorectal carcinomas caused by APC mutation?

A
  1. First hit: mutation of one APC copy
  2. Second hit: mutation of second copy of APC (leads to adenoma formation)
  3. Further mutations (eg in KRAS and p53) in the adenoma –> malignant transformation
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4
Q

Risk factors for colorectal cancer?

A
  1. Diet: ↓ fibre + ↑ refined carbohydrate
  2. Inflammatory bowel disease
  3. Familial: FAP, HNPCC, Peut-Jeghers
  4. Smoking
  5. Genetic (one first degree relative makes it 50 times more likely)

NOTE:
NSAIDS/ Aspirin are protective

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5
Q

What type of carcinoma are the majority of colorectal cancers?

A
  • 95% adenocarcinoma

- others: lymphoma, GIST, carcinoid

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6
Q

The 3 common sites for colorectal cancers?

A

Rectum: 35%
Sigmoid: 25%
Caecum and ascending colon: 20%

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7
Q

Symptoms of colorectal cancer?

A 
Left sided cancer: 
- Altered bowel habit
- PR mass
- Obstruction 
- bleeding/ mucus
Right sided cancer:
- Anaemia
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8
Q

Examination findings of colorectal cancer?

A 
Palpable mass
Perianal fistulae
Hepatomegaly 
Anaemia
Signs of obstruction
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9
Q

Anal fistula

A
  • a narrow tunnel with its internal opening in the anal canal and its external opening in the skin near the anus
  • an abnormal communication bnormal communication between the epithelialised surface of the anal canal and (usually) the perianal skin
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10
Q

Investigations for colorectal carcinoma?

A
  1. Bloods:
    I. FBC: Hb
    II. LFTs: mets
    III. Tumour Marker: CEA (carcinoembryonic Ag)
  2. Imaging
    I. CXR: mets
    II. Ultrasound liver: mets
    III. CT or MRI for staging (MRI best for rectal Ca and liver mets)
    IV. Endoanal ultrasound: staging rectal tumours
    V. Ba / gastrograffin enema: apple-core lesion
  3. Endoscopy + biopsy:
    I. flexi sigmoid: 65% of tumours accessible
    II. colonoscopy
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11
Q

DUKES staging of colorectal cancer?

A

A. confined to bowel wall
B. through bowel wall but not lymph nodes
C. regional lymph nodes
D. distant mets

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12
Q

TNM staging of colorectal cancer?

A 
TIS: carcinoma in situ
T1: submucosa
T2: muscularis propria
T3: subserosa
T4: through the serosa to adjacent organs
N1: 1-3 nodes
N2: >4 nodes
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13
Q

Grading of colorectal cancer?

A

Grading from low to high

  • Based on cell morphology
  • Dysplasia, mitotic index, hyperchromatism
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14
Q

Pre-operative preparation for colorectal cancer resection surgery?

A

I. Kleen Prep (Macrogol: osmotic laxative) the day before and phosphate enema in the morning of surgery.
II. discuss stomas (Stoma nurse consult for siting)

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15
Q

Surgical options for rectal cancer management?

A
  1. Anterior resection:
    - used for upper rectum (tumour 4-5cm from anal verge)
    - takes out rectum and anus
    - needs loop ileostomy
  2. Abdominoperineal resection:
    - used for lower rectum ( tumour <4cm from anal verge)
    - leaves the anus untouched! but takes the rectum out
    +/- 3. Total mesorectal excision (TME)
    - removal of mesorectum
    - for tumours of the middle and lower third of rectum
    - it reduces the cancer recurrence
    - Side effect: ↑ risk of faecal incontinence
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16
Q

Mesorectum?

A

is the perirectal fat separated by the rectal fascia

17
Q

Surgical options for tumours in the following:

  1. sigmoid
  2. Left sided
  3. Transverse
  4. caecal (right sided)
A

1/ Sigmoid: high anterior resection or sigmoid colectomy

  1. Left: left hemicolectomy
  2. Transverse: extended right hemicolectomy
  3. Caecal / right: right hemicolectomy
18
Q

Screening programs for colorectal cancer?

A

I. FOB (faecal occult blood) Testing

  • involves taking a sample from two separate bowel motions
  • 60-75yrs
  • Home FOB testing every 2yrs: ~1/50 have +ve FOB
  • Colonoscopy if +ve: ~1/10 have Ca

II. Flexi Sigmoidoscopy

  • 55-60yrs
  • Once only
19
Q

Genetics of Familial adenomatous polyposis (FAP) ?

A
  • Autosomal dominant

- Mutated APC gene

20
Q

Presentation features of Familial adenomatous polyposis (FAP) ?

A
  • 100-1000s of adenomas by ~16yrs,
  • mainly in large bowel (But also stomach and duodenum, near ampula)
  • 100% develop colorectal cancer, often by ~40yrs
21
Q

Variants of Familial adenomatous polyposis (FAP) ?

A
  1. attenuated FAP
  2. Gardener’s syndrome
  3. Turcot’s syndrome
22
Q

Attenuated FAP?

A
  • <100 adenomas,

- leads to CRC at a later stage (>50yrs)

23
Q

Gardener’s syndrome 4 features?

A

A variant of FAP
TODE
- Thyroid tumours
- Osteomas of the mandible, skull and long bones
- Dental abnormalities: supernumerary teeth
- Epidermal cysts

24
Q

Turcot’s syndrome?

A
  • A variant of Fap

- CNS tumours: medullo- and glio-blastomas

25
Q

Management of Familial adenomatous polyposis (FAP) ?

A

I. Prophylactic colectomy before 20yrs
II. Total colectomy + ileorectal anastomosis (IRA)
III. Proctocolectomy + ileal pouch anal anastomosis (IPAA)
IV. Regular endoscopic screening as remain at risk of Cancer in stomach and duodenum

26
Q

Proctocolectomy + ileal pouch anal anastomosis (IPAA)?

A
  • removal of rectum and large colon and then
  • surgical construction of internal reservoir; near where the rectum would be
  • folding loops of small intestine (the ileum) back on themselves and stitching them together.
  • The internal walls are removed
  • retains or restores functionality of the anus with stools passed under voluntary control of the patient
27
Q

Hereditary Non-Polyposis Colorectal Cancer (HNPCC) genetics?

A
  • Autosomal dominant

- Mutation of mismatch repair enzymes (eg MSH2)

28
Q

Presentation of Hereditary Non-Polyposis Colorectal Cancer (HNPCC) ?

A

Lynch 1 syndrome: right sided colorectal carcinoma (CRC)

Lynch 2 syndrome: CRC + gastric, endometrial, prostate, breast

29
Q

Diagnosis of Hereditary Non-Polyposis Colorectal Cancer (HNPCC)

A

“3, 2, 1, rule”
≥3 family members
over 2 generations
with one <50yrs

30
Q

Peutz-Jeghers Syndrome genetics?

A
  • Autosomal dominant

- STK11 mutation

31
Q

Age of presentation of Peutz-Jeghers Syndrome?

A

at the age of ~ 10-15yrs

32
Q

Symptoms of Peutz-Jeghers Syndrome?

A 
I. Mucocutaneous hyperpigmentation
- Macules on palms, buccal mucosa
II. Multiple GI hamartomatous polyps
- Intussusception
- Haemorrhage
33
Q

Risk associated with Peutz-Jeghers Syndrome?

A

↑ Cancer risk:

  • Colorectal
  • pancreas
  • breast
  • lung
  • ovaries
  • uterus
34
Q

Different types of GI polyps?

A

I. Inflammatory pseudopolyps
II. Hyperplastic polyps
III. Hamartomatous
IV. neoplastic

35
Q

What are inflammatory pseudopolyps?

A

regenerating islands of mucosa in ulcerative colitis

36
Q

What are hyperplastic polyps?

A
  • Piling up of goblet cells and absorptive cells

- No malignant potential

37
Q

What are Hamartomatous polyps

A
  • Tumour-like growths composed of tissues present at site where they develop
  • Sporadic or part of familial syndromes
38
Q

Tenesmus?

A
  • refers to cramping rectal pain

- Tenesmus makes patient feel like they need to have a bowel movement, even if they had one recently

MS3 - GI (16 decks)

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