Common GI malignancies and imaging of the GI tract Flashcards
Where in the oesophagus can you get adenocarcinomas?
Lower third
What is adenocarcinoma?
A malignant tumour formed from glandular structures in epithelial tissue
What is the cause of adenocarcinomas in the lower oesophagus?
Metaplasia over time of normal squamous epithelium to columnar epithelium (containing goblet cells) caused by the chronic reflux of acid into the oesophagus (Barrett’s oesophagus)
Where in the colon would cancer most likely result in a patient presenting with bowel obstruction?
Sigmoid colon
What do right-sided colon tumours tend to be like?
Fungating, exophytic (grow outwards from bowel wall) and prone to bleeding but do not normally cause bowel obstruction. Also the content of the bowel is less solid at this stage - contains more water, therefore is less likely to get blocked.
What do left-sided colon tumours tend to be like?
To grow circumferentially around the lumen of the bowel and cause stenosis and therefore more likely to be blocked. In addition the colons contents are more solid at this stage as more water has been reabsorbed.
What is a commonly used staging system for many cancers?
TNM staging system
In the TNM staging system, what does T stand for?
T describes the primary tumour and the extent of growth
In the TNM staging system, what does N stand for?
N describes the regional lymph node involvement
In the TNM staging system, what does M stand for?
M describes the presence (or not) of distant metastasis
A signet ring cell is a type of cell found on histological images of gastric adenocarinoma. In which histological classification of gastric cancer is it found?
Diffuse type carcinoma
What creates the distinctive appearance of a signet ring cell in certain forms of diffuse gastric cancer?
These cells have had their nucleus pushed to the periphery due to accumulation of intracellular mucin
Describe what happens in diffuse carcinomas
They are usually composed of chains of single cells which invade the wall of the gut without a sharply defined invasive margin
How do intestinal type carcinomas differ from diffuse type carinomas?
Intestinal type carcinomas develop a more glandular structure lined by mucus secreting cells. They tend to have a better define margin than diffuse type carcinomas
What is the most common location for a lymphoma to develop within the GI tract?
Stomach (whilst still fairly rare). They seem to have strong links with H-pylori and in a few cases can be shrunk by eradication the bacteria
What is a lymphoma?
any of a group of blood cell tumors that develop from lymphatic cells
What type of rare pancreatic cancer would cause the patient to have a low blood sugar?
Insulinoma
What is the name of the tumour that causes Zollinger-Ellinson syndrome?
Gastrinoma which produces gastrin. Increased gastrin stimulates an increase in HCl production by the parietal cells and causes severe ulceration of the stomach and small intestine
What is another type of rare pancreatic islet cell cancer, other than insulinoma?
Glucagonoma - secretes excess glucagon
Although largely replaced by TMN staging criteria, Dukes staging (A-D) is still a useful way of thinking about colorectal cancer. What Dukes staging describes a tumour that has penetrated through the muscle layer in the bowel wall?
B - The tumour has gone through the bowel wall but there are no lymph nodes involved
What is the C stage of Dukes staging?
C - Lymph nodes are involved
What is the D stage of Duke’s staging?
D - widespread metastasis
What happens to the 5 year survival rate from cancer as Dukes staging goes from A-D?
It decreases
Where in the oesophagus can you get a adenocarcinoma?
Lower third - if metaplasia from squamous epithelia to columnar epithelia has happened over time (Barrett’s oesophagus) due to chronic reflux, adenocarcinomas (cancer in glandular epithelia) can occur.
Cancer arising in what part of the panceas can cause jaundice to develop?
Head - can block the common bile duct, therefore a similar effect to a gallstone in terms of jaundice
Where do 75% of pancreatic cancers develop?
Head or neck
Where in the GI tract would an ulcerating tumour most likely cause malaena?
Upper GI tract - release haemoglobin into the gut which is then altered by the digestive process and gut bacteria to form black sticky faeces.
An ulcerating tumour in the oesophagus can cause malaena but if the bleeding is rapid the patient may end up vomiting blood
What is haematemesis?
Vominting up blood
What is malaena?
Faces that is black in colour and has a tarry consistency due to it containing haemoglobin (blood) that has been altered by the digestive process and gut bacteria
What type of tumour is more likely to cause haematochezia (passing fresh blood)
Rectal tumour
What are adenomas?
Adenomatous polyps - benign tumours which develop in large numbers (100s-1000s), mainly in the large intestine, in the AD condition familial adenomatous polyposis (FAP). They have the potential to become malignant
Individuals with familial adenomatous polyposis (FAP) are certain to develop what type of cancer by the age of 40?
Colonic cancer and therefore must undergo colectomy before that occurs
What is the most common location for a lymphoma to develop within the GI tract?
Stomach - gastric lymphomas are the most common (though still fairly rare) and seem to have a strong link with H-pylori and in a few cases have been shrunk by eradicating the bacteria
The liver is a common recipient for metastatic spread from other parts of the GI tract. What mode of metastatic spread accounts for this fact?
Haematogenous - all the blood from the gut drains through the liver (via the portal vein). The liver is a common site for secondary deposits metastising via the haematogenous route
What gastrointestinal cancer has the highest incidence in the UK (males and females)?
Colorectal, closely followed by oesophagus and stomach
What cancer (all types) has the highest incidence in women?
Breast cancer
What cancer (all types) has the highest incidence in men?
Prostate cancer
Which cell type do the majority of pancreatic tumours develop from?
Ductal cells (ductal adenocarcinomas) = 80% of pancreatic tumours, but acinar cell carcinoma and islet cell tumours (also known as pancreatic neuroendocrine tumours) are rare but do exist.
What is a carcinoma?
A type of cancer that develops from epithelial cells
What would be a clinical symptom of a narrowing of the lumen of the oesophagus by an oesophageal tumour?
Greater difficulty swallowing foods than liquids. Fluids may become harder to swallow (progressive dysphagia) as the tumour grows (as well as affecting solid foods)
What is the second most common GI cancer?
Stomach
Why is the prognosis for pancreatic cancer so poor?
It is most often diagnosed in its advanced stages because of its late presentation
What is the third most common GI cancer?
Oesophagus
When imaging the GI tract. What are plain X-rays mainly used for?
Investigating an acute abdomen. You can see:
- Air under the diaphragm (in erect position)
- Distended loops of small bowel or colon segments
- Retroperitoneal calification ( may present in acute pancreatitis)
- Faecal loading can be seen (constipation)
What is air under the diagram (in erect position) in a plain X-ray indicate?
Perforation of hollow viscus
List the 5 types of barium contrast studies that can be undertaken on the GI tract
Barium swallow - oesophagus
Double contrast barium meal - stomach and duodenum
Small bowel follow through - gross small intestine
Small bowel enema - small bowel strictures
Barium enema - entire colon
What is the role of a barium swallow contrast study?
To visualise motility abnormalities and anatomical lesions.
When are barium contrast studies performed?
After an overnight fast
What is the use of different position in a barium swallow contrast study?
Upright and prone visualisation of barium swallowing. Reflux of barium from the stomach to the oesophagus can be observed when the patient is tipped head down.
What is the role of a double contrast barium meal?
To examine the stomach and duodenum.
How is a double contrast barium meal given?
A small amount of barium is given together with effervescent granules or tablets to produce carbon dioxide. A double contrast between air and barium is obtained.
What is the role of a small bowel follow through barium contrast study?
Barium is swallowed and allowed to pass through into the small intestine through the jejunum and into the ileum. This is useful to observe the gross anatomy of the small intestine.
What is the role of a small bowel enema contrast study?
A tube is passed through the duodenum and a large volume of dilute barium is introduced. This technique is useful when there is a suspicion of obstruction, to evaluate the strictures
What is the role of a barium enema?
To obtain a double-contrast view of the whole colon
How is a barium enema performed?
Patients are given a low fibre diet for 3 days and the colon thoroughly cleansed with oral laxative preparations. Barium and air are blown in (insufflated) via a rectal catheter.
What are the purposes of the techniques of ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI) in visualising the gastrointestinal tract?
They are used to define organs and detect thickened bowel wall, masses, abscesses or fistulae.
What are the uses of ultrasound in visualising the GI tract?
It does not require radiation and is best to visualise fluid-filled structures in acute abdomen:
Cholecystitis
Aortic aneurysm
Appendicitus
(Thickened bowel can be visualised without mucosal detail)
What are the uses of computed tomography (CT)?
It gives excellent definition of the anatomy (thickened bowel walls, mesentery, retroperitoneal structures, aorta).
It can be used to detect: perforated viscus, subdiaphragmatic abcesses, extraluminal abscesses in appendicitis and diverticulitis.
Contrast extravasated from the gut lumen, as well as free air, can bet detected.
What are the uses of magenetic resonance imaging (MRI)?
Doesn’t use ionising radiation.
Particularly useful for evaluating abscesses and fistulae in the perianal region. It is commonly used in hepatobiliary and pancreatic diseases
Which techniques used to visualise the GI tract do not use ionising radiation?
MRI and ultrasound
What does angiography allow to be visualised?
Gastrointesinal vascular system
How is angiography performed?
Puncture, canulisation and injection of a radio-opaque contrast medium into a blood vessel
