Colorectal cancer Flashcards
Risk Factors?
-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
What is FAP?
-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).
What is Hereditary nonpolyposis colorectal cancer (HNPCC) ?
- 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.
Bowel cancer presentation?
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
What is the referral criteria for the two week wait?
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
Patients may present acutely with obstruction if the tumour blocks the passage through the bowel. This presents a surgical emergency with vomiting, abdominal pain and absolute constipation.
What is the bowel cancer screening?
-Faecal immunochemical tests (FIT) look very specifically for the amount of human haemoglobin in the stool.
-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
-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.
Investigations?
-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.
-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.
-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.
-Staging CT scan involves a full CT thorax, abdomen and pelvis (CT TAP). This is used to look for metastasis and other cancers. It may be used after a diagnosis of colorectal cancer, or as part of the initial workup in patients with vague symptoms (e.g., weight loss) in addition to colonoscopy as an initial investigation to exclude other cancers.
-Carcinoembryonic antigen (CEA) is a tumour marker blood test for bowel cancer. This is not helpful in screening, but it may be used for predicting relapse in patients previously treated for bowel cancer.
Describe TNM classification?
T for Tumour:
TX – unable to assess size
T1 – submucosa involvement
T2 – involvement of muscularis propria (muscle layer)
T3 – involvement of the subserosa and serosa (outer layer), but not through the serosa
T4 – spread through the serosa (4a) reaching other tissues or organs (4b)
N for Nodes:
NX – unable to assess nodes
N0 – no nodal spread
N1 – spread to 1-3 nodes
N2 – spread to more than 3 nodes
M for Metastasis:
M0 – no metastasis
M1 – metastasis
Management (surgical) ?
-Laparoscopic surgery (where possible) generally gives better recovery and fewer complications compared with open surgery. Robotic surgery is increasingly being used, which is essentially a more advanced laparoscopic procedure.
Surgery involves:
Identifying the tumour (it may have been tattooed during an endoscopy)
Removing the section of bowel containing the tumour,
Creating an end-to-end anastomosis (sewing the remaining ends back together)
Alternatively creating a stoma (bringing the open section of bowel onto the skin)
Operations available?
Operations
Right hemicolectomy involves removal of the caecum, ascending and proximal transverse colon.
Left hemicolectomy involves removal of the distal transverse and descending colon.
High anterior resection involves removing the sigmoid colon (may be called a sigmoid colectomy).
Low anterior resection involves removing the sigmoid colon and upper rectum but sparing the lower rectum and anus.
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.
Hartmann’s procedure is usually an emergency procedure that involves the removal of the rectosigmoid colon and creation of an colostomy. The rectal stump is sutured closed. The colostomy may be permanent or reversed at a later date. Common indications are acute obstruction by a tumour, or significant diverticular disease.
Complications of surgery?
Bleeding, infection and pain
Damage to nerves, bladder, ureter or bowel
Post-operative ileus
Anaesthetic risks
Laparoscopic surgery converted during the operation to open surgery (laparotomy)
Leakage or failure of the anastomosis
Requirement for a stoma
Failure to remove the tumour
Change in bowel habit
Venous thromboembolism (DVT and PE)
Incisional hernias
Intra-abdominal adhesions
Low Anterior Resection Syndrome?
Low anterior resection syndrome may occur after resection of a portion of bowel from the rectum, with anastomosis between the colon and rectum. It can result in a number of symptoms, including:
Urgency and frequency of bowel movements
Faecal incontinence
Difficulty controlling flatulence
Follow up?
Patients will be followed up for a period of time (e.g., 3 years) following curative surgery. This includes:
Serum carcinoembryonic antigen (CEA)
CT thorax, abdomen and pelvis
Management (not surgery)?
Chemotherapy
Radiotherapy
Palliative care
