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Alimentary system > Cancer of the gut > Flashcards

Cancer of the gut Flashcards

1
Q

Describe what is meant by cancer

A

a disease caused by an uncontrolled division of abnormal cells in a part of the body

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2
Q

Distinguish between primary and secondary (metastatic cancers)

A

Primary
Arising directly from the cells in an organ
Secondary/Metastasis
Spread from another organ, directly or by other means (blood or lymph)

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3
Q

Describe cancers of the epithelial cells in the G.I tract

A

§ Squamous — Squamous cell carcinoma

§ “Glandular epithelium” — Adenocarcinoma

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4
Q

Describe the cancers of the neuroendocrine cells in the G.I tract

A

§ EnteroChrommafin cells —- Carcinoid tumours

§ Interstitial cells of Cajal —- GI Stromal tumours

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5
Q

Describe the cancers of connective tissue in the G.I tract

A

§ Smooth muscle — Leiomyoma/leiomyosarcomas

§ Adipose tissue – - Lipoma

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6
Q

What happens as you go down the oesophagus

A

Increased smooth muscle/ reduced skeletal muscle

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7
Q

List some common G.I cancers

A 
Oesophageal
Stomach
Biliary system
Pancreatic
Colorectal - small intestine, large intestine, colon and anus
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8
Q

Describe the situation with liver cancers

A

Few liver cancers are rarely primary- high blood flow so lots of cancers from the G.I tract can metastasize there

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9
Q

Summarise oesophageal anatomy

A

Divided into thirds
Cervical oesophagus – narrow

Middle oesophagus- impressions form aorta and left main bronchus

Lower oesophagus- impressions from left atrium

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10
Q

Describe squamous cell carcinoma of the oesophagus

A

From normal oesophageal squamous epithelium
Upper 2/3
Acetaldehyde pathway
Less developed world

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11
Q

Describe adenocarcinoma of the oesophagus

A

From metaplastic columnar epithelium
Lower 1/3 of oesophagus
Related to acid reflux
More developed world

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12
Q

What is the most common epithelium of the G.I tract

A

Glandular epithelium
Distal oesophagus, small bowel, large bowel
Adenocarcinomas therefore most common - particular in colorectal cancer

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13
Q

Compare cancers of the chromaffin cells to interstitial cells of Cajal

A

chromaffin cells are more benign

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14
Q

List some symptoms of oesophageal cancer

A

Long history of heart burn, regurgitation and burping
Difficulty and pain when swallowing
Weight loss - due to lack of nutrition
Pain in the breast bone and stomach, or a feeling of reflux
In later stages, further symptoms include:
Nausea, vomiting, and regurgitation of food
Vomiting blood, due to trauma to the tumour

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15
Q

Describe adenocarcinomas of the oesophagus

A

Related to acid reflux - repeated damage to the epithelium. Also associated with obesity, but due to unknown cause, tobacco smoking and alcohol consumption.
Occurs 10 times more frequently in men, possibly due to hormonal control in women, and more often in the developed world.

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16
Q

Describe squamous cell carcinomas of the oesophagus

A

Main causes are tobacco smoking and chewing, alcohol consumption, and ingestion of caustic substances.
The link to alcohol is due to the acetaldehyde metabolite, which damages the epithelial cells. This is more common in the Asian population, where mutations in the acetaldehyde dehydrogenase enzyme leads to build up of this metabolite, increasing the risk of cancer.

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17
Q

What is acid reflux linked to

A

Obesity- increased abdominal pressure forces the acid up

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18
Q

What is regurgitations

A

Food coming back up and being swallowed again

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19
Q

Outline the progression from reflux to adenocarcinoma

A

Oesophagitis (inflammation) - due to chronic exposure to acid (15% of population will have GORD)
Due to injury, ongoing inflammation and cytokine drive this can progress to Barret’s oesophagus (5-13% of GORD)
5% of these will progress to dysplasia each year
And 0.5%-30% of these will progress to carcinoma

20
Q

What is important about swallowing

A

The textures of what they can swallow

Achalasia- failure of LOS to relax

21
Q

Outline the clinical investigations for oesophageal cancer

A

Endoscopy, called an ‘oesophagogastroduodenoscopy’. Includes using a camera to observe the tumour, and a biopsy to evaluate the cells by histology
CT scan to check for metastasis
Endoscopic ultrasound - to determine level of invasion

22
Q

List the risk factors for colon cancer

A

Family History
Inflammatory bowel disease (Crohns, ulcerative colitis)
Specific inherited conditions
Familial adenomatous polyposis, Hereditary non-polposis colon cancer, Lynch Syndrome
Uncontrolled Ulcerative Colitis
Age (>50)
Previous Polyps

23
Q

Describe the progression of colon cancer

A

Normal epithelium — hyperproliferative epithelium with aberrant cryptic foci (due to APC mutation often induced by aspirin, other NSAIDS, folate and calcium)- will overexpress COX-2

This can progress to a small adenoma (again due to aspirin and other NSAIDS)

A k-ras mutation induced by estrogens and aspirin can result in the formation of a large adenoma

p53 mutation and loss of 18q can cause progression to colon carcinoma

24
Q

Summarise the pathology of colon cancer

A

Not a single gene process

Sequence of genetic errors
APC, K-ras, p53, 18q

Inheritance therefore not simple Mendelian

25
Q

List the symptoms of colorectal cancer

A

Asymptomatic (incidental anaemia)- blood loss in G.I tract can be occult- you may not notice it

Change in Bowel Habit
Diarrhoea
Constipation

Blood in Stool

Acute intestinal obstruction

Loss of appetite
Loss of weight
Nausea and Vomiting

26
Q

Which symptoms are not associated with colorectal cancer

A

Rectal bleeding with anal symptoms
Itch
Soreness / discomfort
External lump
prolapse
Change in bowel habit to harder or less frequent stool
Abdominal pain in the absence of obstruction

Positive findings at colonoscopy are as frequent as for completely asymptomatic age matched control

27
Q

Outline the investigations for colorectal cancer

A 
A: Abdominal X-Ray
B: CT Scan
C: Barium enema
D: Colonoscopy- ate primarily with a COLONOSCOPY 
E: CT Virtual colonoscopy
28
Q

Describe blood in the stool

A

o Bright blood probably from the colorectal area so is not that bad.
o Black or dark blood in stool is much more concerning as from early bowel.

29
Q

Describe the use of an abdominal X-Ray

A

Cheap
Easy
Quick

Sensitivity for obstruction 77%
Specificity for obstruction 50%
So not that useful

30
Q

Describe the use of a plain CT

A

Quick
Easy
See large lesions

May miss smaller lesions
No tissue
No therapy

31
Q

Describe the use of barium enema

A

Reasonable Sensitivity and Specificity

Time Intensive
Technically demanding
Unacceptable to patients- may have to poo out a double cream like substance afterwards

32
Q

Describe the procedure for a barium enema

A

Tube up bottom- pump up barium- roll them on their side- allows you to see the colon - better sensitivity and specificity than a plain CT
Can do a double contrast- pump air up bowel afterwards- to see the lining of the bowel afterwards

33
Q

Describe the use of colonoscopy

A

Safe
Relatively quick
High Sensitivity
Able to obtain tissue

2 days of iatrogenic diarrhoea
Small risk of perforation (<1:2000)
Risk of dehydration
Can be technically challenging- moving a rigid tube in a tube that can move- need a roadmap

34
Q

How can you identify caecum

A

Appendix
Tri-radiate folds
Ileo-caecal valve

35
Q

What is bowel prep

A

horrendous diahhroea- to clear bowel - if not done properly you will not get decent views

36
Q

Describe CT virtual colonoscopy

A

Drink barium- put them through CT scanner- poo labelled with bismuth- subtracted

Modified (reduced) bowel prep

“tag” stool using Bismuth

Computer aided subtraction to create images

37
Q

Describe the use of CT virtual colonoscopy

A

Quick
Easy
Reduced Bowel prep more tolerable
As good as colonoscopy for lesions >6mm

Unable to obtain tissue
Unable to remove lesions- will need colonoscopy to get tissue and then remove the polyp

38
Q

How can we remove the polyps

A

Current through base of polyp
If we cut through it will bleed
saline injected into wall to remove polyp from wall

39
Q

Summarise pancreatic cancer

A

“Silent Killer”
Non specific symptoms

Virchow’s triad
Pain – 70%
Anorexia – 10%
Weight loss – 10%

40
Q

List the early symptoms for pancreatic cancer

A

Abdominal pain
Depression

Glucose intolerance

41
Q

List the late symptoms for pancreatic cancer

A

Weight loss
Jaundice
Ascites
Obstructed gall bladder

Not much you can do here

42
Q

Describe the outcomes for pancreatic cancer

A

Outcome is poor:
Only 20% are suitable for a resection when they present
Surgery is curative in 20-25% of cases- part of duodenum removed, pancreas removed, gall bladder removed, have to be very fit-
1 year survival 18%
5 year survival 2%

43
Q

List the risk factors for pancreatic cancer

A 
Smoking
Drinking
Obesity
Family
Especially rare conditions such as MEN  (multiple endocrine neoplasia)
44
Q

Describe the surveillance for oesophageal cancer

A

4 biopsies every 1cm along segment. Aspirin would reduce COX2 expression
§ Barrett’s Oesophagus – NO dysplasia:
o Every 3-5 years.
§ Barrett’s Oesophagus – Low-grade dysplasia:
o Every 6 months until NO dysplasia.
§ Barrett’s Oesophagus – High-grade dysplasia:
o Flat – Radio Frequency Ablation (e.g. HALO – RFA in a 360 motion in oesophagus).
o Nodular – endoscopic mucosal resection, then HALO.

Can give aspirins and PPIs to reduce COX-2 expression

45
Q

Describe low grade dysplasia

A

4% of those with Barret’s
1.5 % of patients with low grade dysplasia progress to high grade

0.5% progress to oesophageal adenocarcinoma

46
Q

Describe the treatment for oesophageal cancer

A

Surgery
In early stages, the tumour may be removed from the oesophageal wall
Oesophagectomy - removal of part of the oesophagus
Chemotherapy and radiotherapy

47
Q

Describe the treatment for colorectal cancer

A

Surgery - removal of the tumour via colonoscopy or laparotomy. This may result in removal of large parts of the colon, resulting in a colostomy.
Chemotherapy and radiotherapy

Alimentary system (15 decks)

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