Colorectal tumours Flashcards
How prevalent is colorectal cancer?
3rd most common cancer worldwide
Fill in the gap: colorectal cancer is the __ most common cause of cancer death in the UK
2nd
What type of cancers are most colorectal tumours?
adenocarcinomas
What is the most common cause of adenocarcinoma transitions in the bowel?
chromosomal instability (CIN)
What is chromosomal instability?
The sequential accumulation of genetic mutations of tumour suppressor genes and oncogenes
Name 2 tumour suppressor genes associated with colorectal cancer:
1) APC
2) TP53
Name 2 oncogenes associated with colorectal cancer:
- BRAF
- KRAS
The mutation of which gene often triggers the cancerous pathway in the bowel?
APC (adenomatous polyposis coli)
Give 8 risk factors for colorectal cancer:
- Family history
- IBD
- Smoking and alcohol
- Hereditary non-polyposis colorectal cancer
- Familial adenomatous polyposis
- diet
- Increase age
- Obesity
Describe a high risk diet for colorectal cancer:
high in red and processed meat and low in fibre
Is familial adenomatous (FAP) autosomal dominant or recessive?
dominant
what gene is mutated in FAP?
APC
Describe familial adenomatous polyposis:
a defect in the APC gene causing many polyps to form in the large intestine - these polyps have the potential to become cancerous
What prophylactic treatment is offered to patients diagnosed with FAP?
they have a full colectomy to prevent development of bowel cancer
What is another name given to hereditary non-polyposis colorectal cancer (HNPCC)
Lynch Syndrome
Is HNPCC autosomal dominant or recessive?
Dominant
Describe HNPCC:
a hereditary condition that results in mutations of DNA mismatch repair genes that puts patients at a high risk for a number of cancers, particularly colorectal cancers
What % of colorectal cancers are caused by FAP?
less than 1%
What % of colorectal cancers are caused by HNPCC?
2-3%
Where are most colorectal cancers found in the large intestine?
sigmoid colon and rectum
Give 7 clinical features associated with colorectal cancer:
1) persistant and unexplained change in bowel habit
2) rectal bleeding
3) abdominal pain
4) abdominal bloating
5) unexplained weight loss
6) fatigue
7) iron deficiency anaemia
True or false: unexplained iron deficiency anaemia warrants a two week wait referral for urgent cancer testing
True
What referral process is used for red flags of colorectal cancer?
two week wait urgent cancer referral
When would a colorectal cancer patient present acutely to hospital?
obstruction (tumour blocks the passage through the bowel - surgical emergency)
Give 3 acute symptoms associated with a colorectal cancer obstruction:
1) vomiting
2) abdominal pain
3) absolute constipation
What is the GP test and screening program tool for bowel cancer?
FIT testing (faecal immunochemical tests)
What group of people are included in the England bowel cancer screening program?
people aged 60-74 are sent a home FIT test every 2 years
What is the gold standard investigation for colorectal cancers?
colonoscopy with biopsy of suspicious lesions
What is the name given to endoscopy of the rectum and sigmoid colon only?
sigmoidoscopy
What imaging technique may be considered for patients less fit for a colonoscopy?
CT colonagraphy
What imaging technique is often used to visualise metastases for staging?
CT TAP (thorax, abdomen, pelvis)
What tumour marker is sued to predict relapse in patients previously treated for colorectal cancer?
carcinoembryonic antigen (CEA)
Give an overview of the TNM staging system used in colorectal cancer:
1) tumour - the degree of intestinal wall invasion
2) nodes - lymph node involvement
3) the presence of distant metastases
Give the four main treatment options for colorectal cancer:
1) surgical resection
2) chemotherapy
3) radiotherapy
4) palliative care
What type of surgery is used to resect colorectal cancers?
laparoscopic surgery
Describe the steps in colorectal cancer resection: (4)
1) the tumour is identified
2) the section of bowel containing the tumour is removed
3) the remaining ends are sewed back together (anastomosis)
4) OR a stoma is created by bringing an open section of the bowel onto the skin
Give 4 potential complications of bowel cancer surgery:
) damage to nerves, bladder, ureter or bowel
2) DVT and PE
3) infection
4) incisional hernias
What is low anterior resection syndrome:
a condition that may occur after resection of a portion of the bowel from the rectum with anastomosis between the colon and rectum
Give 3 presentations associated with low anterior resection syndrome:
1) urgency and frequency of bowel movements
2) faecal incontinence
3) difficulty controlling flatulence
Give 4 complications associated with colorectal cancer:
1) metastasis
2) bowel obstruction
3) bowel perforation
4) fistulas
What is the most common site of metastasis for cancer in the large intestine?
liver
What is the most common site of metastasis for rectal cancer?
thoracic organs and nervous system
