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GI - Y2 > L14 - Screening of GI cancer > Flashcards

L14 - Screening of GI cancer Flashcards

1
Q

Describe familial adenomatous polypsosis?

A
  • autosomal dominant
  • results from germ line mutation of tumour supressor gene, APC gene followed by acquired mutations from remaining allele
  • mutation … truncated APC protein
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2
Q

Describe the normal role of APC and its role after mutation?

A

Normally
- APC binds and isolates B-catenin

After mutation

  • can’t bind and isolate B-canetin
  • B-canetin transolcates into nucleus
  • causes upregulation of many genes
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3
Q

What is the MUTYH gene?

A

Involved in base excision repair.
May give rise to colonic polyposis.
Autosomal recessive inheritance.

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4
Q

Describe a desmoid tumour?

A

Abnormal growth that arises from connective tissue

- benign? may become very big causing compression of adjacent organs.

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5
Q

CHRPE - congenital hypertrophy of retinal pigment epithelium

A
  • dark round pigmented retinal lesions.

- if present in at risk person it is 100% indicative of FAP

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6
Q

Turcot’s syndrome

A

Condition characterized by multiple adenomatous colon polyps, an increased risk of colorectal cancer and an increased risk of brain cancer.

May be associated with FAP.

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7
Q

Peutz-Jegher syndrome

A

Many harmatomatous polyps occur in small intestine and colon.
- melanin pigmentation of lips, mouth, digits

Asymptomatic usually but:

  • chronic bleeding
  • anaemia
  • intussusception: where one segment of small intestine telescopes inside another/
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8
Q

Harmatoma

A

Benign, local malformation of cell resembling neoplasm of local tissue.
Usually due to an overgrowth of multiple aberrant cells.

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9
Q

Peutz-Jegher syndrome results from

A

Shortening mutation in serine-threonine kinase gene on chromosome 19p (STK11)

Autosomal dominant

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10
Q

Describe the occurrence of juvenile polyposis

A
  • caused by germline mutations in the SMAD 4 gene
  • family history of polyps
  • colorectum contains many mucous filled hamartomatous polyps
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11
Q

Describe the dietary risk factors for colorectal cancer

A

Increased risk

Red meat : high saturated fat and protein, carcinogenic amines formed in cooking

Saturated animal fat: increased faecal bile and fatty acid level

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12
Q

Describe what kind of diet may decrease the risk of colorectal cancer?

A

Calcium
Folic acid: reverses DNA hypomethylation
Green veg: anti-carcinogen (flavonoid)

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13
Q

Risk factors for colorectal cancer

A
  • obesity
  • smoking
  • cholecystecotomy (effect of bile acid in right colon)
  • type 2 diabtes
  • use of NSAIDs, COX-2 inhibitors
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14
Q

Compare left and right colon tumours?

A 
RHS 
- anaemia
- occult bleeding 
- altered bowel habit 
- obstruction is a late feature 
LHS 
- fresh rectal bleeding 
- obstruction occurs early
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15
Q

Signs of carcinoma of rectum

A

Early bleeding
Mucus discharge.
Feeling of incomplete emptying.

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16
Q

Prevention and screening of colon tumours

A

FOB: faecal occult blood test, checks for blood in faeces
Colonoscopy - gold standard
Flexible sigmoidoscopy - flexible tube inserted into the rectum

17
Q

Diverticula

A

Protrusion of mucosa covered by peritoneum.

18
Q

What may cause diverticulosa?

A
  • deficiency in fibre
  • small vol stools need increases in intracolonic pressure for propulsion.
  • leads to herniation of mucosa between the taenia coli.
  • hypertrophy of circular muscle coat
  • inflammation, impact of diverticula with faecolith (hard stony faeces in intestinal tract)
19
Q

Diverticulosa may progress to…

A 
Haemorrhage 
Perforation 
Local abscess formation 
Fistula 
Peritonitis
20
Q

Investigation of GI disease: what may be seen on CXR

A
  • dilated loops of bowel in erect position
  • calcified lymph nodes
  • gall stones
  • renal stones
21
Q

Describe use of endoscopic USS

A
  • Increased frequency transducer produces high res USS images
  • allows visualisation through wall of GI tract and into surrounding tissue.
  • can be used to perform fine needle aspiration
  • used for biopsy of mass lesion
22
Q

Describe capsule endoscopy

A
  • Wireless, traverses small intestine.
  • transmits images to battery powered recorder worn as a belt on patient.
  • 8hr approx for capsule to be secreted
23
Q

Describe endoscopic retrograde cholangiopancreatography?

A
  • duodenoscope cannulates main pancreatic duct and common bile duct
24
Q

How may anti-inflammatory drugs reduce cancer risk?

A
  • nSAIDS inhibits prostaglandin synthesis by blocking cyclo-oxygenase COX
  • link between chronic inflammation and carcinogenesis
25
Q

Where are prostaglandins derived from and what is their role?

A

Prostaglandin’s derived from arachidonic pathway.
During inflammation PGE2 increases vasodilation and increases microvascular permeability - leading to redness and swelling.

Maintenance of gastroduodenal defence.

26
Q

Celecoxib

A

works by:

  • inhibiting COX-2 while sparing COX-1
  • hene avoiding side effects of COX-1 inhibition

low dose aspirin will irreversibly inhibit platelet aggregation.

27
Q

Action of nitric oxide on gastric mucosa

A

Increases and maintains gastric mucosal blood flow.
Stimulates mucus secretion.
Inhibits neutrophil adherence.

28
Q

Types of screening

A

Mass screening
- whole population or large subgroup
Targeted screening
- high risk groups

29
Q

Lead time bias

A

Appearance that early diagnosis of a disease prolongs survival with that disease.
However diagnoses happen roughly at the same time regardless.

30
Q

Length time bias

A

Over estimation of survival duration due to the relative excess of cases detected that are asymptotically slowly progressing.

While fast progressing cases are detected after giving symptoms.

31
Q

Components of NHS Bowel cancer screening

A

Bowel scope
- one-off flexible sigmoidoscopy >55 y/o

National bowel cancer screening

  • Fecal occult blood test (FOB)
  • Fecal immunochemical test (FIT)
32
Q

What is a loop diathermy?

A

Biopsy taken using thin loop of electrified wire to remove abnormal cells.

  • procedure known as a large loop excision of the transformation zone (LLETZ)
33
Q

Argon plasma coagulation

A

Medical endoscopic procedure used to control bleeding from certain lesions in the GI tract.

34
Q

Focal lesion

A

Lump / bump can be removed

35
Q

Multifocal dysplasia

A

Squamous cell (pale pink), converted to dark pink columnar epithelium.

36
Q

Argon plasma coagulation

A

Endoscopic procedure.
Jet of ionized argon (plasma) directed through a probe passed through endoscope.

Probe placed at some distance from bleeding lesion.

Argon gas emitted then ionized by a high voltage discharge.

Results in coagulation of bleeding lesion.

37
Q

HALO Radiofrequency ablation

A

Use of radiowaves to destroy the dysplasia.

Can be used to treat entire area of Barrett’s oesophagus

38
Q

Describe an innovative test for Barrett’s oesophagus?

A

Cytosponge.

  • Pile swallowed, expands into small rough textured sponge in the stomach.
  • sponge pulled back up collecting some cells lining food pipe.
  • sent to lab for analysis

GI - Y2 (18 decks)

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