Colorectal cancer Flashcards
What is colorectal cancer?
Colorectal cancer is the third most common type of cancer in the UK and the second most cause of cancer deaths.
How many new cases of colorectal cancer are diagnosed annually in the UK?
Annually, there are about 150,000 new cases diagnosed.
How many deaths are caused by colorectal cancer each year in the UK?
There are about 50,000 deaths from colorectal cancer each year.
What are common presenting features of colorectal cancer?
Common presenting features include change in bowel habits, rectal bleeding, abdominal pain, unexplained weight loss, anaemia, and bowel obstruction.
What changes in bowel habits may indicate colorectal cancer?
Patients may experience constipation, diarrhoea, or alternating between the two, and may feel the need for more frequent bowel movements.
What does rectal bleeding in colorectal cancer look like?
Blood in the stool may be bright red or melena.
What abdominal symptoms may occur with colorectal cancer?
Patients may experience abdominal pain, cramping, or discomfort due to tumour obstruction or inflammation.
What is a sign of advanced colorectal cancer?
Unexplained weight loss can be a sign of advanced disease.
How can colorectal cancer lead to anaemia?
Chronic bleeding from the tumour can lead to anaemia, causing fatigue, weakness, and shortness of breath.
What happens in advanced cases of colorectal cancer?
The tumour can completely obstruct the bowel, causing severe abdominal pain, nausea, and vomiting.
What are the average locations of colorectal cancer?
Rectal: 40%, Sigmoid: 30%, Descending colon: 5%, Transverse colon: 10%, Ascending colon and caecum: 15%.
What are the three types of colon cancer?
- Sporadic (95%)
- Hereditary non-polyposis colorectal carcinoma (HNPCC, 5%)
- Familial adenomatous polyposis (FAP, <1%)
What genetic mutations are associated with sporadic colon cancer?
Sporadic colon cancer may be due to a series of genetic mutations, including allelic loss of the APC gene, activation of the K-ras oncogene, and deletion of p53 and DCC tumour suppressor genes.
What is HNPCC and its characteristics?
HNPCC (Lynch syndrome) is an autosomal dominant condition and the most common form of inherited colon cancer. Around 70-80% of patients develop cancers, often of the proximal colon, which are usually poorly differentiated and highly aggressive.
What genes are commonly involved in HNPCC?
The most common genes involved in HNPCC are MSH2 (60% of cases) and MLH1 (30%).
What are the Amsterdam criteria for diagnosing HNPCC?
- At least 3 family members with colon cancer
- Cases span at least two generations
- At least one case diagnosed before the age of 50 years
What is FAP and its implications?
FAP is a rare autosomal dominant condition leading to the formation of hundreds of polyps by the age of 30-40 years, inevitably resulting in carcinoma.
What gene mutation causes FAP?
FAP is due to a mutation in the adenomatous polyposis coli gene (APC), located on chromosome 5.
What is the typical surgical intervention for FAP patients?
Patients generally undergo a total proctocolectomy with ileal pouch anal anastomosis (IPAA) formation in their twenties.
What additional risks do FAP patients face?
Patients with FAP are also at risk of duodenal tumours.
What is Gardner’s syndrome?
Gardner’s syndrome is a variant of FAP that can feature osteomas of the skull and mandible, retinal pigmentation, thyroid carcinoma, and epidermoid cysts on the skin.
What factors influence the management strategies for colorectal cancer?
Management strategies depend on the tumour’s location, stage, histological type, and the patient’s overall health status.
What staging tests should be performed for newly diagnosed colorectal cancer?
All patients should have carcinoembryonic antigen (CEA), CT of the chest, abdomen and pelvis, evaluation of the entire colon with colonoscopy or CT colonography, and MRI for those with tumours below the peritoneal reflection.
What is the TNM staging system used for?
The TNM (Tumour, Node, Metastasis) staging system is commonly used to stage colorectal cancer, aiding in prognosis and treatment planning.
What is the primary treatment for colon cancer?
Cancer of the colon is nearly always treated with surgery, specifically resectional surgery.
What factors influence the choice of surgical procedure for colon cancer?
The procedure is tailored to the patient and the tumour location, with confounding factors such as familial history influencing the choice.
What are the key technical factors for anastomosis healing?
Key factors include adequate blood supply, mucosal apposition, and no tissue tension.
What options are available when a colonic cancer presents with an obstructing lesion?
The options are to either stent it or resect.
What are the types of resections based on the site of cancer?
Caecal, ascending or proximal transverse colon: Right hemicolectomy (Ileo-colic); Distal transverse, descending colon: Left hemicolectomy (Colo-colon); Sigmoid colon: High anterior resection (Colo-rectal); Upper rectum: Anterior resection (TME) (Colo-rectal); Low rectum: Anterior resection (Low TME) (Colo-rectal); Anal verge: Abdomino-perineal excision of rectum (None).
When is chemotherapy used in colorectal cancer treatment?
Chemotherapy is used in the neoadjuvant setting, adjuvant setting, and for metastatic disease.
What are common chemotherapy regimens for colorectal cancer?
Common regimens include FOLFOX and FOLFIRI.
What is the primary use of radiation therapy in colorectal cancer?
Radiation therapy is predominantly used for rectal cancers in the neoadjuvant or adjuvant setting.
What targeted therapies are used for metastatic colorectal cancer?
Bevacizumab (anti-VEGF) and Cetuximab (anti-EGFR) are used, particularly for metastatic disease.
What is the risk associated with anastomosis in emergency surgery for perforated bowel?
The risk of anastomosis is much greater, particularly for colon-colon anastomosis, leading to the preference for an end colostomy.
What is a Hartmann’s procedure?
When resection of the sigmoid colon is performed and an end colostomy is fashioned, the operation is referred to as a Hartmann’s procedure.
Are ileo-colic anastomoses safe in emergency settings?
Ileo-colic anastomoses are relatively safe even in the emergency setting and do not need to be defunctioned.
What did NICE update in 2023 regarding colorectal cancer referral guidelines?
NICE updated their referral guidelines to increase the use of Faecal Immunochemical Test (FIT) testing instead of always doing a colonoscopy first-line.
In which scenarios should a FIT be used to guide referral?
A FIT should be used to guide referral in the following scenarios:
- with an abdominal mass,
- with a change in bowel habit,
- with iron-deficiency anaemia,
- aged 40 and over with unexplained weight loss and abdominal pain,
- aged under 50 with rectal bleeding and unexplained abdominal pain or weight loss,
- aged 50 and over with unexplained rectal bleeding, abdominal pain, or weight loss,
- aged 60 and over with anaemia even in the absence of iron deficiency.
What is an important point regarding FIT testing?
FIT testing should be offered even if the person has previously had a negative FIT result through the NHS bowel cancer screening programme.
Do patients with certain conditions need to be offered FIT before referral?
No, patients with a rectal mass, an unexplained anal mass, or unexplained anal ulceration do not need to be offered FIT before referral.
What should be done if the FIT test result is positive?
If the FIT test result is positive, the patient should be referred on the suspected cancer pathway.
What should be done if the FIT test result is negative?
If the FIT test result is negative, safety netting is recommended, and NICE suggests referring on the suspected cancer pathway if there is ongoing significant concern.
What is the NHS national screening programme for colorectal cancer?
The NHS has a national screening programme offering screening every 2 years to all men and women aged 60 to 74 years in England and 50 to 74 years in Scotland. Patients aged over 74 years may request screening.
What type of test is the Faecal Immunochemical Test (FIT)?
The FIT is a type of faecal occult blood (FOB) test that uses antibodies to specifically recognise human haemoglobin (Hb) and is used to detect and quantify the amount of human blood in a single stool sample.
What happens if a patient has abnormal results from the FIT test?
Patients with abnormal results from the FIT test are offered a colonoscopy.
Who else is the FIT test recommended for?
The FIT test is recommended for patients with new symptoms who do not meet the 2-week criteria, such as:
- patients >= 50 years with unexplained abdominal pain or weight loss,
- patients < 60 years with changes in bowel habit or iron deficiency anaemia,
- patients >= 60 years who have anaemia even in the absence of iron deficiency.
What is the primary development of most colorectal cancers?
Most colorectal cancers develop from adenomatous polyps.
How much has screening for colorectal cancer reduced mortality?
Screening for colorectal cancer has been shown to reduce mortality by 16%.
What screening method does the NHS offer to older adults?
The NHS offers home-based, Faecal Immunochemical Test (FIT) screening to older adults.
What trial was abandoned in 2021 regarding colorectal cancer screening?
A one-off flexible sigmoidoscopy trial at the age of 55 years was abandoned in 2021.
Why was the flexible sigmoidoscopy trial abandoned?
It was abandoned mainly due to an inability to recruit enough clinical endoscopists, exacerbated by the covid-19 pandemic.
What did the trial funded by Cancer Research UK show?
The trial had shown promising early results.
What is the age range for the NHS national screening programme in England?
The NHS now offers screening every 2 years to all men and women aged 60 to 74 years in England.
What is the age range for the NHS national screening programme in Scotland?
In Scotland, the screening is offered to individuals aged 50 to 74 years.
Can patients over 74 years request screening?
Yes, patients aged over 74 years may request screening.
How are eligible patients notified for FIT tests?
Eligible patients are sent Faecal Immunochemical Test (FIT) tests through the post.
What does the FIT test detect?
The FIT test detects and quantifies the amount of human blood in a single stool sample.
What is an advantage of the FIT test over conventional FOB tests?
The FIT test only detects human haemoglobin, unlike conventional FOB tests which can detect animal haemoglobin ingested through diet.
How many faecal samples are needed for the FIT test?
Only one faecal sample is needed for the FIT test, compared to 2-3 for conventional FOB tests.
What information is reported to the patient or GP from the FIT test?
Patients are informed if the test is normal or abnormal, but the numerical value is not reported.
What happens to patients with abnormal FIT test results?
Patients with abnormal results are offered a colonoscopy.
What are the findings at colonoscopy?
Approximately 5 out of 10 patients will have a normal exam, 4 out of 10 will have polyps, and 1 out of 10 will be found to have cancer.
Site of cancer, type of resection, anastomosis
