Lower GI tumours Flashcards
What type of tumours occur in the small intestine?
Malignant:
- adenocarcinoma
- Non-Hodgkin’s lymphoma
- Carcinoid
Benign:
- Peutz-Jeghers syndrome
- Adenomas, Leiomyomas, Lipomas
- FAP
What are the symptoms of small intestine tumours?
Abdominal pain Diarrhoea Anorexia Anaemia Malabsorption
Where in the small intestine do adenocarcinomas most commonly occur?
In the duodenum
What are the risk factors of cancer of the small intestine?
Crohn's disease Coeliac disease Family history Poor lifestyle: smoking, alcohol, diet Radiation exposure
What cells does Non-Hodgkin’s lymphoma affect in the small intestine?
The lymphocytes: either B or T
What is the treatment for NHL and adenocarcinoma?
Surgical resection
Chemotherapy + Radiotherapy if needed
What is Peutz-Jeghers syndrome?
A genetic condition, autosomal dominant
Consists of:
- mucocutaneous pigmentation (hands, feet)
- hamartomatous benign GI polyps
Peutz-Jeghers syndrome causes GI polyps, where in the GI system do they most occur?
Small intestine
Why do you need to be concerned about Peutz-Jeghers syndrome?
The polyps can bleed or cause intussusception (telescoping)
Also they can become malignant
What is an:
- adenoma
- leiomyoma
- lipoma?
Adenoma: benign tumour formed of glandular structures in epithelial tissue
Leiomyoma: benign tumour formed of smooth muscle
Lipoma: benign tumour formed of fatty tissue
What are carcinoid tumours of the small intestine?
A type of neuroendocrine tumour
Malignant tumours of cells of the neuro and endocrine system
What cells do carcinoid s. intestine tumours arise from?
What’s the normal function of these cells?
How does the tumour affect these cells’ functions?
Enterochromaffin cells
They release serotonin
In the small intestine
Causes excess release of serotonin
Describe the function of healthy enterochromaffin cells?
They are found around the small intestine
When they sense food in the lumen they release serotonin which makes the gut contract around the food, pushing it down
When they detect an irritant in food they release more serotonin to make food move through even faster, this is what causes diarrhoea
What is carcinoid syndrome?
Symptoms caused by the over-secretion of serotonin caused by a carcinoid tumour
Carcinoid syndrome occurs in all patients with carcinoid tumours of the small intestine.
True or false?
False
It only occurs if they have liver metastases
In about 5% of patients
Why does carcinoid syndrome occur?
It occurs when the liver loses the ability to metabolise the excess serotonin
So the serotonin builds up and causes symptoms
What are the clinical features of carcinoid syndrome?
Flushing
Wheezing
Diarrhoea
Abdominal pain
Right heart valvular fibrosis: tricuspid, pulmonary valves
Stenosis + regurgitation
Investigations of carcinoid syndrome?
Urine sample: you will see high levels of 5-HIAA which is the breakdown product of serotonin
USS: will show liver metastases
Management of carcinoid syndrome?
Somatostatin analogues: octreotide
Reducing tumour mass surgically
Chemotherapy
What tumours occur in the colon + rectum?
Adenocarcinoma Squamous cell carcinoma Carcinoid tumours Sarcoma Non-Hodgkin Lymphoma
Which is the most common colorectal cancer?
Adenocarcinoma
What are the risk factors for colon cancer?
Familial colon cancer disorders
Family history of colorectal cancer IBD: Crohn's + UC Diet: low fibre, lots of red meats Alcohol Smoking
What is sarcoma?
Cancer of connective tissue: in the colon they are usually leiomyosarcomas: smooth muscle tumour
What are the familial colon cancer disorders?
FAP: Familial Adenomatous Polyposis
HNPCC: Hereditary Non-polyposis Colorectal Cancer
What is FAP and why does it cause colorectal cancer?
Familial Adenomatous Polyposis
Genetic condition in which they develop thousands of polyps in the colon at an early age
Having these polyps puts you at an increased risk of one of them becoming malignant - colon cancer
They will usually get colon cancer during their 20s
What is the pathophysiology of FAP?
Adenomatous polyposis colon protein (APC) is affected
Usually APC prevents levels of the protein beta canenin getting too high by binding to it
If beta canenin levels get too high the protein moves to the nucleus, damages DNA causing adenomas
Which protein is mutated in FAP?
APC
Adenomatous polyposis colon protein
How can you treat FAP?
Total colectomy: removal of bowel
What is HNPCC and why does it cause colorectal cancer?
Hereditary non-polyposis colorectal cancer
They are born without a copy of a gene that codes for a protein that finds and fixes DNA errors in the body
So DNA damage is not detected and fixed so it is allowed to cause adenomas
Adenomas then lead to malignancy
Why is chemotherapy unsuccessful in HNPCC?
Because chemo damages DNA and relies on the body’s repair proteins to find and fix the damage
If they don’t have these proteins they can’t find the damage so it is not fixed and can lead to malignancy
Which part of the colon are tumours most commonly found?
Left side
The side closest to rectum
Clinical features of colorectal cancer?
Depends on site
Left:
- bleeding and mucus
- altered bowel habit
- obstruction
- tenesmus
- colicky pain
- thinner stools
Right side:
- weight loss
- iron deficiency anaemia
- pain
Why is obstruction more common in left colon tumours than right?
Right sided tumours tend to be exophytic (they grow outwards into lumen)
The bowel is stretchy so can accommodate meaning now obstruction occurs
Left-sided tumours tend to be circumferential (grow around bowel lumen) they constrict the bowel. Bowel can’t accommodate so obstruction occurs
Signs of metastatic disease
Why do left sided colon cancers cause thin stools?
Because the tumours usually grow circumferentially, constricting the bowel
Why do right sided colon cancers usually present with iron deficiency anaemia initially?
Anaemia is caused by blood loss
Because R sided tumours don’t cause obstruction people don’t notice them until they are advanced enough to cause anaemia
Describe the progression of normal gut epithelia to malignant colorectal adenocarcinoma?
Normal epithelium
Adenoma
Colorectal adenocarcinoma
What are adenomas (specific to colon)? Who gets them?
Benign growth of glandular epithelium in the colon
1/3rd of people over 60 have them
People with genetic conditions like FAP
Do all adenomas lead to malignancy?
No!
But the more you have the more chance you have of one developing into an adenocarcinoma
Investigations of colorectal cancer?
Bloods: FBC to look for anaemia
Faecal occult blood: look for presence of blood in stools
Barium enema to show up blockage
Endoscopy: flexible sigmoidoscopy or colonoscopy
CT/MRI to look for mets
DNA test if suspect genetic cause (FAP/HNPCC)
Where to colorectal cancers often metastasise to?
Liver
Lung
Bone
How are colorectal cancers usually classified?
Duke’s classification
TNM
Explain Duke’s classification?
Stages A-D
A = limited to the innermost muscle layer of bowel wall, the muscularis mucosa
B = extension through the muscle layer
C = spread to at least one lymph node close to bowel
D = metastasised to other part of body
Management of colorectal cancer?
Surgical resection of segment tumour is and anastomosis of remaining bowel
Sometimes colostomy is required
Post-operative adjuvant chemotherapy helps in cancers with local or lymph spread
Pre-operative radiotherapy can help shrink the tumour
Metastatic cancer: you can try to remove metastases but often its best to go for palliative care
Which people are eligible to bowel cancer screening in the UK?
Men and women aged 60-74
People with family history
