Gastrointestinal cancer

Question 1

Three most common sites of cancer in the GI system:

Answer 1

o Oesophageal cancer.
o Colon cancer.
o Pancreatic cancer

Question 2

Cancers in relation to cell types:

Answer 2

Epithelial cells:
▪ Squamous: Squamous cell carcinoma
▪ “Glandular epithelium”: Adenocarcinoma

Neuroendocrine cells:
▪ EnteroChrommafin cells: Carcinoid tumours
▪ Interstitial cells of Cajal: GI Stromal tumours

Connective tissue:
▪ Smooth muscle: Leiomyoma/leiomyosarcomas
▪ Adipose tissue: Lipoma

Question 3

2 types of cancer in oesophageal cancer

Answer 3

1) Squamous Cell Carcinoma:
o Upper 2/3 of oesophagus.
o Forms from normal oesophageal squamous epithelium.
o Acetaldehyde pathway.
o More common in LESS developed world.

2) Adenocarcinoma:
o Lower 1/3 of oesophagus.
o Forms from metaplastic columnar epithelium.
o Related to acid reflux.
o More common in MORE developed world.

Question 4

Progression of oesophageal cancer

Answer 4

Oesophagitis (Inflammation)→ Barrett’s (metaplasia)→ Dysplasia→ Carcinoma (neoplasia)

Question 5

How would oesophageal cancer be identified?

Answer 5

would be identified by endoscopy, OGD or gastroscopy.

Question 6

Barrett’s oesophagus

Answer 6

Barrett’s oesophagus is a metaplasia from repeated exposure to stomach acid.
o Replacement of squamous cell mucosa → columnar mucosa.

Question 7

▪ Overall risk of adenocarcinoma in Barrett’s oesophagus

Answer 7

0.12%/yr.

Question 8

▪ Post-low grade dysplasia risk of adenocarcinoma =

Answer 8

0.5%/yr.

Question 9

▪ Post-high grade dysplasia risk of adenocarcinoma =

Answer 9

5-30%/yr.

Question 10

Surveillance Protocol for oesophageal cancer

Answer 10

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.

Question 11

Colorectal cancer risk factors

Answer 11

▪ Age – Biggest risk factor (over 50).
▪ Family history or specific inherited conditions (e.g. FAP, HNPCC, Lynch Syndrome).
▪ Uncontrolled ulcerative colitis.
▪ Previous polyps.

Question 12

Progression of colorectal cancer

Answer 12

▪ Normal (+ mutation) → hyper proliferative epithelium → small adenoma (+ mutation) → large adenoma (+ mutation) → colon adenoma (+ small cancerous invasion).
▪ Aspirins will reduce the COX2 over expression.
▪ This is not a single gene process, this is a sequence of genetic errors:
o APC → K-ras → p53 → 18q loss.
o Inheritance is therefore NOT simple Mendelian.

Question 13

Symptoms of colorectal cancer

Answer 13

Normally totally asymptomatic (with unknown iron-deficient anaemia = 5-10% chance of cancer).
▪ Change in bowel habit - e.g. diarrhoea (worse) or constipation.
▪ Blood in stool:
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.
▪ Acute intestinal obstruction.
Symptoms that aren’t cancer include rectal bleeding with itch, soreness etc., change in bowel habits to harder or less frequent stool, abdominal pain in absence of obstruction.
Usually will investigate primarily with a COLONOSCOPY

Question 14

Colorectal cancer investigations
Advantages of each one
Disadvantages of each one

Answer 14

▪ Abdominal x-ray:
o Advantages: cheap | easy | quick.
o Disadvantage: Not very sensitive and specific (even at late stage)

▪ CT scan:
o Advantages: quick | easy | see large lesions.
o Disadvantages: could miss small lesions | cannot take samples and cannot carry out treatment.

▪ Barium enema:
o Advantages: quite sensitive and specific.
o Disadvantages: time insensitive | technically demanding | unacceptable for patients: VERY messy and they have to poo out a double cream like substance after.

▪ Colonoscopy:
o Advantages: safe | quick | high sensitivity | able to obtain tissue.
o Disadvantages: 2 prep days of iatrogenic diarrhoea | small risk of perforation | small risk of dehydration.

▪ Virtual colonoscopy:
o Advantages: Quick | easy | reduced bowel prep so more tolerable | good for lesions greater than 6mm.
o Disadvantages: unable to obtain tissue | unable to remove lesions.

Question 15

Symptoms of pancreatic cancer

Answer 15

▪ Usually asymptomatic but people with this cancer present with:
o Pain in 70%.
o Anorexia in 10%.
o Weight loss in 10%.
▪ Associated symptoms can be; jaundice, new diabetes, lost weight etc.
o Jaundiced because enlargement on the head of the pancreas
impinges on the common bile duct → diabetes and jaundice.

Question 16

Symptoms and outcomes of pancreatic cancer

Answer 16

Symptoms and Outcomes.
▪ EARLY – abdominal pain, depression, glucose intolerance (pancreas issues).
▪ LATE – weight loss, jaundice, ascites (fluid building up in the peritoneum due to inflammation in the peritoneum),
obstructed gall bladder.
▪ Prognosis is VERY poor…
o Only 20% resectable (lose all endo- and exocrine function) and surgery only curative 20-25% of cases.
o 1-year survival rate 18%, 5-year survival rate 2%.

Question 17

Risk factors of pancreatic cancer

Answer 17

Smoking.
Drinking.
Obesity.
Family.