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.