Colorectal Cancer Flashcards
How common is bowel cancer?
Bowel cancer is the fourth most prevalent cancer in the UK, behind breast, prostate and lung cancer.
What does bowel cancer refer to?
Bowel cancer usually refers to cancer of the colon or rectum.
What are the risk factors for bowel cancer?
There are a number of factors that increase the risk of colorectal cancer:
- Family history of bowel cancer
- Familial adenomatous polyposis (FAP)
- Hereditary nonpolyposis colorectal cancer (HNPCC)
- Also known as Lynch syndrome
- Inflammatory bowel disease (Crohn’s or ulcerative colitis)
- Increased age
- Diet (high in red and processed meat and low in fibre)
- Obesity and sedentary lifestyle
- Smoking
- Alcohol
Give examples of hereditary syndromes that are linked to bowel cancer
- Familial adenomatous polyposis
- Hereditary nonpolyposis colorectal cancer (Lynch Syndrome)
- Juvenile polyposis
- Peutz-Jeghers syndrome
Briefly describe familial adenomatous polyposis (FAP)
Familial adenomatous polyposis (FAP) is an autosomal dominant condition involving malfunctioning of the tumour suppressor genes called adenomatous polyposis coli (APC). It results in many polyps (adenomas) developing along the large intestine. These polyps have the potential to become cancerous (usually before the age of 40). Patients have their entire large intestine removed prophylactically to prevent the development of bowel cancer (panproctocolectomy).
Briefly describe hereditary nonpolyposis colorectal cancer (HNPCC)
Hereditary nonpolyposis colorectal cancer (HNPCC) is also known as Lynch syndrome. It is an autosomal dominant condition that results from mutations in DNA mismatch repair (MMR) genes. Patients are at a higher risk of a number of cancers, but particularly colorectal cancer. Unlikely FAP, it does not cause adenomas and tumours develop in isolation.
What are the red flag clinical features that may indicate bowel cancer?
The red flags that should make you consider bowel cancer are:
- Change in bowel habit (usually to more loose and frequent stools)
- Unexplained weight loss
- Rectal bleeding
- Unexplained abdominal pain
- Iron deficiency anaemia (microcytic anaemia with low ferritin)
- Abdominal or rectal mass on examination
Briefly describe the NICE guidelines for two week wait referral for suspected bowel cancer
The NICE guidelines for suspected cancer recognition and referral give various criteria for a “two week wait” urgent cancer referral, depending on the patient’s age and combination of symptoms. For example:
- Over 40 years with abdominal pain and unexplained weight loss
- Over 50 years with unexplained rectal bleeding
- Over 60 years with a change in bowel habit or iron deficiency anaemia
Why is iron deficiency anaemia a key clincal finding for bowel cancer?
Iron deficiency anaemia on its own without any other explanation (i.e. heavy menstruation) is an indication for a “two week wait” cancer referral for colonoscopy and gastroscopy (“top and tail”) for GI malignancy. This is because GI malignancies such as bowel cancer can cause microscopic bleeding (not visible in bowel movements) that eventually lead to iron deficiency anaemia.
Briefly describe faecal immunochemical tests (FIT) and its use
Faecal immunochemical tests (FIT) look very specifically for the amount of human haemoglobin in the stool. FIT replaced the older stool test called the faecal occult blood (FOB) test, which detected blood in the stool but could give false positives by detecting blood in food (e.g., from red meats).
FIT tests can be used as a test in general practice to help assess for bowel cancer in specific patients who do not meet the criteria for a two week wait referral, for example:
- Over 50 with unexplained weight loss and no other symptoms
- Under 60 with a change in bowel habit
Briefly describe the screening for bowel cancer in the UK
FIT tests are used for the bowel cancer screening program in England. In England, people aged 60 – 74 years are sent a home FIT test to do every 2 years. If the results come back positive they are sent for a colonoscopy.
People with risk factors such as FAP, HNPCC or inflammatory bowel disease are offered a colonoscopy at regular intervals to screen for bowel cancer.
What is the gold standard investigation for bowel cancer?
Colonoscopy is the gold standard investigation.
Briefly describe the use of colonoscopy for investigating bowel cancer
Colonoscopy is the gold standard investigation. It involves an endoscopy to visualise the entire large bowel. Any suspicious lesions can be biopsied to get a histological diagnosis, or tattoo in preparation for surgery.
Briefly describe the use of sigmoidoscopy for investigating bowel cancer
Sigmoidoscopy involves an endoscopy of the rectum and sigmoid colon only. This may be used in cases where the only feature is rectal bleeding. There is the obvious risk of missing cancers in other parts of the colon.
Briefly describe the use of CT colonography for investigating bowel cancer
CT colonography is a CT scan with bowel prep and contrast to visualise the colon in more detail. This may be considered in patients less fit for a colonoscopy but it is less detailed and does not allow for a biopsy.
Briefly describe a right hemicolectomy
Right hemicolectomy involves removal of the caecum, ascending and proximal transverse colon.
Briefly describe a left hemicolectomy
Left hemicolectomy involves removal of the distal transverse and descending colon.
Briefly describe a right anterior resection
High anterior resection involves removing the sigmoid colon (may be called a sigmoid colectomy).
Briefly describe a low anterior resection
Low anterior resection involves removing the sigmoid colon and upper rectum but sparing the lower rectum and anus.
Briefly describe a abdomino-perineal resection (APR)
Abdomino-perineal resection (APR) involves removing the rectum and anus (plus or minus the sigmoid colon) and suturing over the anus. It leaves the patient with a permanent colostomy.
