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Year 2 > Cancer Of The GI Tract > Flashcards

Cancer Of The GI Tract Flashcards

1
Q

What is bowel cancer?

A

The second most common cancer and the most common bowel malingancy.

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2
Q

What is the taenia coli?

A

Bands of longitudinal smooth muscle on the walls of the colon from the appendix to the sigmoid colon which facilitate efficient contraction of circular muscle.

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3
Q

What are the haustra?

A

Pouches which give the colon its segmented appearance that is activated by the presence of chyme. to

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4
Q

What are the epiploic appendices?

A

Small pouches of peritoneum filled with fat on the colon.

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5
Q

What are the intraperitoneal organs?

A

First part of duodenum, jejunum, ileum, transverse colon and sigmoid colon. They are covered by visceral peritoneum and the outermost layer is the serosa.

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6
Q

What are the retroperitoneal organs?

A

Distal duodenum, ascending colon and descending colon. The outermost layer is the adventitia which binds organs to the abominable wall.

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7
Q

What is the histology of the oesophagus?

A

Mucosal layer is composed of stratified squamous epithelia that contains a lamina propia and muscularis mucosae.
Below this is the submucosa.
Muscularis propia
Adventitia

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8
Q

What is an important structure in the submucosa of the oesophagus?

A

Meissener’s plexus, which is the network of nerves which innervate the glands for secretion. The submucosa of the oesophagus contains goblet cells and is a highly vascular layer formed of loose connective tissue.

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9
Q

What is an important structure in the mucosa of the oesophagus?

A

The upper portion of the oesophagus has a muscularis propia layer containing skeletal striated muscle, which transitions into smooth muscle and between these changes is the transition zone. The outer muscles are arranged longitudinally and the inner muscles are arranged circularly, and between these layers is the myenteric plexus of Auerbach’s plexus.

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10
Q

What is Auerbach’s plexus?

A

Myenteric plexus in between the circular and longitudinal muscles of the muscularis layer in the GI tract to control peristalsis.

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11
Q

What is the upper oesophageal sphincter?

A

Located between the pharynx and oesophagus to control the passage of food, which is composed of skeletal muscle. Epithelia here are stratified squamous.

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12
Q

What is the lower oesophageal sphincter?

A

Located between the oesophagus and stomach, composed of smooth muscle. Epithelia transition here from stratified squamous to simple columnar.

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13
Q

What is the most common oesophageal cancer?

A

Squamous cell carcinoma, that typically occurs in the middle 1/3rd of the oesophagus. Risk factors are alcohol, hot drinks, smoking and over 60s.

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14
Q

What reduces the risk of squamous cell carcinoma of oesophageal cancer?

A

Diet rich in fruit and vegetables and dietary fibre.

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15
Q

What is the cause of adenocarcinoma of the oesophagus?

A

Typically due to a weak lower oesophageal sphincter which is a consequence of gastrointestinal oesophageal reflux disease (GERD) where gastric acid entering the oesophagus at the lower junction causes damage and metaplasia from squamous cell epithelia -> columnar epithelia over time.

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16
Q

What are the risk factors for Barrett’s oesophagus?

A

Obesity
Tobacco use
Alcohol
Hiatal hernia

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17
Q

What is hiatal hernia?

A

Protrusion of the stomach through an opening in the diaphragm into the oesophagus.

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18
Q

What are the clinical features of oesophageal cancer?

A

Elderly patients which have progressive dysphagia, odynophagia. It causes progressive weight loss and haematemesis (bloody vomit) which can progress to anaemia. Because it is diagnosed late so there is poor prognosis and has already metastasised, requiring CT scan

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19
Q

What is odynophagia?

A

Pain when swallowing

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20
Q

What are the types of gastric cancer?

A

Gastric cancers are typically adenocarcinomas divided into:
Intestinal type
Infiltrative type

21
Q

What is intestinal type gastric cancer?

A

Caused by increased Wnt signalling pathway for cellular proliferation of intestinal epithelia, involving decreased function mutation of APC gene and increased function of Beta-catenin. This causes bulky tumours that grow into the lumen to form with an ulcerative and glandular structure.

It develops from precursor lesions in the adenoma.

22
Q

What is APC?

A

Tumour suppressor gene, which is dysfunctional in infiltrative gastric cancer.

23
Q

What is the epidemiology of gastric cancer?

A

High frequency in Japan, Korea, Eastern Europe and Northern Europe. Decreasing prevalence in Western countries due to lesser prevalence of Helicobacter pylori, reduced smoked food and salt intake. It is more common in lower socioeconomic groups.

24
Q

What is B-catenin ?

A

Promotes cellular proliferation, and is up regulated in infiltrative gastric cancer.

25
Q

What are the risk factors for gastric cancer?

A

Smoking
Age between 60-80 years old
Male
Diet high in nitrosamine rich foods like smoked meats

26
Q

What is diffuse infiltrative gastric cancer?

A

Caused by a loss of E-cadherin which leads to a mutation in tumour suppressor gene CDH1. This results in infiltration of the mucosa of the stomach, causing a desmoplastic reaction where the stomach fibrosis occurs that causes the texture to resemble a leather bottle (limita plastica) which permeates the stomach wall.

27
Q

What is the role of E-cadherin?

A

Inhibits migration of tumour cells to limit metastasis and tumour progression, regulates CDH1.

28
Q

Which gastric cancer is triggered by helicbacter pylori?

A

Infiltrative gastric cancer. This is due to chronic inflammation that causes chronic gastritis, leading to atrophy and metaplasia. Reactive hyperplasia of gastric cells occurs due to damage that results in precursor polyp formation, which progresses onto dysplasia and eventually adenocarcinomas.

29
Q

What is pancreatic cancer?

A

Progression of adenocarcinoma which typically occurs at the head in the pancreas and frequently metastasises to the lungs, breast and GI system. It typically causes obstructive jaundice and presents in older people 60-80 years old.

30
Q

What is the cause of pancreatic cancer?

A

Typically precursor lesions, from repetitive bouts of acute pancreatitis that leads to intraepithelial neoplasias. Majority are caused by a mutation of the proto-oncogene K-Ras which controls cellular growth and inactivation of CDKN2A, a tumour suppressor gene.

31
Q

What is the typical presentation of pancreatic cancer?

A

Epigastric pain which radiates to the back, with obstructive jaundice. Migratory thrombophlebitis is a sign, indicating Trousseau’s malignancy. It is highly invasive and smoking is the biggest risk factor where surgery is the only option.

32
Q

What is Courvoisier’s sign?

A

Right upper quadrant mass with painless obstructive jaundice, indicates pancreatic cancer.

33
Q

What are the risk factors for colorectal cancer?

A

Male
Older age over 50 years old
Smoking
Alcohol
History of Polyps
-> Most people have no family history, but this can increase the risk.

34
Q

How does a left-sided colon cancer present?

A

It occurs in the descending colon which is narrower , so it causes obstruction, with symptoms like:
Abdominal distention
Cramping
Haematochemezia
Tenesumus
Change in bowel habits

35
Q

What is haematochezia?

A

Passage of fresh blood in the anus through the stools. If it is on the surface, indicates lower GI issue. Within the stools indicates upper GI issue. It is typically a dark red plum colour.

36
Q

What is tenesmus?

A

Incomplete sense of defaecation.

37
Q

How does right sided colon cancer present?

A

Ascending colon is larger, so tumour growth here will lead to chronic bleeding and is associated with:
Fatigue
Pallor
Iron-deficiency anaemia
Tachycardia
Shortness of breath

38
Q

What is FAP?

A

Family Adenomatous Poylposis disease, which typically occurs due to mutation of gatekeeper gene APC, a tumour suppressor. This increases the signalling in the Wrnt pathway for cellular proliferation, that causes a grater rate of Beta-catenin which promotes tumour migration. There is a 100% risk of colorectal cancer, around age 16-20 years old and it is a autosomal dominant condition.

It occurs throughout the colon and rectum.

39
Q

What is HNPCC?

A

Hereditary Non-Polyposis Colorectal carcinoma, where there is a mutation in the DNA mismatch repair genes MSH2 and MLH1. It is an autosomal dominant condition, with no polyps formation, however, there is an 80% risk of colorectal cancer later in life and causes micro satellite instability, affecting the right side of the colon.

40
Q

What is Lynch syndrome?

A

Also known as HPNCC.

41
Q

What is the epidemiology of colon cancer?

A

Higher incidence in Western countries with a diet high in refined foods of carbs, fats and low vegetable fibre. It usually begins as a benign polyp and progresses change in bowel habit, bleeding and pain. Typically occurs in over 50’s and majority are diagnosed through the FIT screening programme.

42
Q

What are the causes of colorectal cancer?

A

Majority are sporadic, due to increased Wnt pathway signalling, as a result of APC gene and Beta-catenin mutations.
APC and HNPCC are rarer causes of colorectal cancer which typically manifest at a younger age.

43
Q

What is the pathophysiology of adenocarcinoma formation in colorectal cancer?

A

First hit mutation of APC gene but there is another functional APC gene so colon histology is normal. Second hit mutation of APC gene occurs which affects Beta-catenin levels and causes abnormal methylation and inactivation of normal alleles.

Eventually, proto—oncogenes like K-RAS become mutated and there is an over expression of COX-2, resulting in adenoma formation in mucosa. As this progresses, there is gross chromosomal abnormalities.

44
Q

What are neoplastic polyps?

A

Present in 30% of Western adults which have the potential to progress to colorectal cancer, therefore colonoscopy is important and the size correlates with the malignancy.

45
Q

Iron deficiency anaemia in older male/ post-menopausal woman?

A

GI cancer.

46
Q

What is the treatment for colorectal cancer?

A

Surgery is the only curative option, but antibody therapy is increasingly being used. Main cause of death of colorectal cancers is metastasise to the liver, as a result of portal circulation. There is a very high survival rate of 94% in Stage 1, which drops dramatically at the later stages

47
Q

What are the features of rectal cancer?

A

Visible bleeding or mucus, with stools containing brighter red blood, and tenesmus is typical. Pain is a poor prognosis.

48
Q

What are the stagings for colorectal cancer?

A

Duke’s system
TNM system

49
Q

What is the Duke’s system?

A

Former classification system from A-D based on the infiltration of the tumour through the mucosal layers of the colon for staging colorectal cancer.

Year 2 (247 decks)

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