Colorectal Cancer Flashcards
What are the risk factors of bowel cancer?
-Most are sporadic with no clear influence
-Some are caused by familial risk
-Some caused by genetic conditions
-Underlying IBD
List some of the risk factors for sporadic cases of colorectal cancer.
Age
Male
Previous adenocarcinoma
Environmental: diet, obesity, diabetes, smoking, lack of exercise
What do the majority of colorectal cancers arise from?
Pre-existing polyps
What are some indications of a high risk polpy?
Size
Number of polyps
Degree of dysplasia (abnormal development).
Villous architecture
Describe how adenocarcinomas can develop from epithelium.
Activation of oncogenes
Loss of tumour suppressor genes
Defective DNA pathway repair genes
What is the presentation of colorectal cancer?
Rectal bleeding- especially mixed in stool
Iron deficiency anaemia
Palpable mass
Weight loss
Altered bowel opening to loose stools >4week
Where would a palpable mass usually be found in those with colorectal cancer?
Rectal or right abominable mass
What is the investigation of choice for colorectal cancer?
Colonoscopy as allows imaging and biopsies to be taken simultaneously
What are patients often given before colonscopy?
Sedation and analgesia as uncomfortable procedure
Which radiological imaging can be used for the investigation of colorectal cancer?
Barium enema
CT colonography- imaging of choice
What are some of the disadvantages of radiological imagining in terms of colorectal cancer?
Ionising radiation
Bowel preparation
No histology
What are the disadvantages of colonoscopy?
Sedation required
Risk of perforation
Bowel preparation
Which imaging technique would be used to help determine staging of cancer in the chest/abdomen/pelvis?
CT
Which imaging technique would be used to help determine staging of cancer in the rectum?
MRI
What is the main treatment for colorectal cancer?
Surgery
What is the management if the cancer has metastases to the liver?
Partial hepatectomy
Discuss the chemo/radiotherapy for patients with rectal cancers.
Radiotherapy combined with chemo before patient undergoes surgery
In terms of palliative care, what might be given?
Chemotherapy
Colonic stenting
Why might colonic stenting be given as a palliative measure?
Relieves chronic obstruction
How is colorectal cancer getting controlled on a population level?
Screening of high risk groups and average high risk population
What is the first part of screening for colorectal cancer?
Faecal tests- either FIT or FOBT
What might happen is someone has signs of colorectal cancer in their screening faecal test?
Will undergo colonoscopy
Which age group get screened for bowel cancer in Scotland?
50-74
Which heritable conditions put individuals at higher risk of developing colorectal cancer?
FAP (familial adenomatous polyposis)
MAP (MUTYH-associated polyposis)
HNPCC (hereditary nonpolyposis colorectal cancer)
Which other groups are considered to have a higher risk and are screened for colorectal cancer?
Individuals with IBD
Familiar risk
Previous adenocarcinomas/ colorectal cancer
Is FAP autosomal dominant or recessive?
Autosomal dominant
What happens in FAP?
Multiple adenomas develop throughout colon usually in childhood, high risk of malignant changes in 20s
How often do those with FAP get screened for colorectal cancer?
Every year from the age of approx. 10-12 via colonoscopy
There are some extracolonic manifestations of FAP. List some.
Benign hyperplastic polyps in stomach.
Duodenal adenocarcinomas.
Which tumours may those with FPA also develop?
Desmoid tumours
Non-cancerous growths in connective tissue
Is MAP autosomal dominant or recessive?
Autosomal recessive
How is MAP similar to FAP?
Polyps develop but tend to be in early adulthood rather than childhood.
How often do those with MAP get screened for colorectal cancer?
Every year from the ages of 18-20.
Upper GI surveillance may occur from 35yrs.
Why may upper GI surveillance occur in those with MAP from 35yrs?
Higher risk of duodenal carcinomas
Is HNPCC autosomal dominant or recessive?
Autosomal dominant
What causes HNPCC?
Mutation in DNA mismatch repair genes
Those with HNPCC also display a condition called microsatellite instability. What does this mean?
Frequent mutations in short repeated DNA sequences.
How often do those with HNPCC get screened for colorectal cancer?
Screening from 25yrs, every 2 years
At which other sites could you get cancer relating to HPNCC?
Stomach
Pancreas
Endometrium
Genitoruinary
How often are those with a family history of colorectal cancer offered screening?
High risk- colonoscopy every 5yrs from age of 50
Low risk- one colonoscopy at 55yrs
How often are those with a IBD offered screening?
10 years after diagnosis, then depends on duration and extend of inflammation.
How often are those with a history of colorectal cancer offered screening?
Colonoscopy one year after surgery and then every three years
How often are those with previous adenocarcinomas offered screening?
Depends on number of polyps, size and degree of dysplasia
Undetectable levels of what could be a good rule out test for significant bowel disease?
Undetectable levels of faecal haemoglobin
