Colorectal Cancer Flashcards
Colorectal cancer (CRC) is the fourth most common malignancy in the UK and a major cause of morbidity and mortality
… (CRC) is the fourth most common malignancy in the UK and a major cause of morbidity and mortality.
CRC account for approximately 11% of malignancies in the UK. Rates generally increase with age and incidence peaks in the …-… age group.
CRC account for approximately 11% of malignancies in the UK. Rates generally increase with age and incidence peaks in the 85-89 age group.
Numerous risk factors are associated with the development of CRC - what are these?
Family history Hereditary syndromes (see below) Inflammatory bowel disease Ethnicity* - Figures from Cancer Research UK indicate that CRC is more common in white people than those of black or asian heritage Radiotherapy Obesity Diabetes mellitus Smoking
A number of hereditary syndromes increase the risk of CRC - what are the two main ones?
A number of hereditary syndromes increase the risk of CRC
Hereditary nonpolyposis colorectal cancer - what is this?
HNPCC, also known as Lynch syndrome, is an autosomal dominant condition responsible for around 3% of CRCs. Common mutations include MLH1, MSH2, MSH6 and PMS2.
Familial adenomatous polyposis - what is this?
FAP is an autosomal dominant condition with penetrance approaching 100% caused by mutations to the adenomatous polyposis coli (APC) gene - a tumour suppressor gene. It is characterised by the development of numerous adenomatous polyps in the colon and rectum, some of which undergo malignant change. 90% will develop CRC before the age of 45 if not treated. Screening is typically commenced at the age of 12-14 with an annual colonoscopy.
MYH-associated polyposis: is an autosomal … condition characterised by colorectal … and cancers caused by a mutation to MYH (MUT Y homologue) gene. MUTYH is a base excision repair gene and failure of its normal action increases the risk of colorectal cancer.
MYH-associated polyposis: is an autosomal recessive condition characterised by colorectal adenomas and cancers caused by a mutation to MYH (MUT Y homologue) gene. MUTYH is a base excision repair gene and failure of its normal action increases the risk of colorectal cancer.
Peutz-… syndrome: is an autosomal dominant condition characterised by hamartomatous polyps in the gastrointestinal tract, pigmented mucocutaneous lesions and an increased risk of gastrointestinal and extragastrointestinal malignancies. Other complications include polyp-related intussusception and small bowel obstruction. There is an estimated 40% lifetime risk of colorectal cancer.
Peutz-Jeghers syndrome: is an autosomal dominant condition characterised by hamartomatous polyps in the gastrointestinal tract, pigmented mucocutaneous lesions and an increased risk of gastrointestinal and extragastrointestinal malignancies. Other complications include polyp-related intussusception and small bowel obstruction. There is an estimated 40% lifetime risk of colorectal cancer.
… polyposis syndrome: is an autosomal dominant condition with incomplete penetrance. It is characterised by hamartomatous polyps throughout the GI tract and an increased risk of CRC and gastric cancer.
Juvenile polyposis syndrome: is an autosomal dominant condition with incomplete penetrance. It is characterised by hamartomatous polyps throughout the GI tract and an increased risk of CRC and gastric cancer.
CRC may be considered … (no clear link above the average population to family history and genetics) or … Some texts and papers will also describe familial CRC - patients in whom there is family history of CRC without fitting one of the known hereditary syndromes. Sporadic CRC is responsible for around …% of CRC, inherited …% and familial …%.
CRC may be considered sporadic (no clear link above the average population to family history and genetics) or inherited. Some texts and papers will also describe familial CRC - patients in whom there is family history of CRC without fitting one of the known hereditary syndromes. Sporadic CRC is responsible for around 70% of CRC, inherited 5-10% and familial 20%.
The majority of colorectal cancers are …, accounting for 90-95% of cases. The colonic epithelium undergoes continuous loss and replacement and mutations may lead to abnormal developments.
The majority of colorectal cancers are adenocarcinomas, accounting for 90-95% of cases. The colonic epithelium undergoes continuous loss and replacement and mutations may lead to abnormal developments. There are multiple pathway to malignancy though the adenoma - carcinoma sequence is common and well described.
CRC most commonly occurs in the rectum and … colon.
CRC most commonly occurs in the rectum and sigmoid colon.
Primary sites - CRC
CRC may arise anywhere along the colon or rectum. Most commonly they affect the left side of the colon.
The disease develops gradually and is asymptomatic for much of its course. As such screening programmes have been introduced (see below) to try and catch the malignancy during this asymptomatic phase.
Features may be subtle and clinicians must be vigilant to pick up symptoms such as change in bowel habit and unexplained weight loss.
Approximately …% of CRC have metastatic spread at diagnosis. The .. is the organ most commonly affected and symptoms of spread here may lead to diagnosis.
Approximately 23-26% of CRC have metastatic spread at diagnosis. The liver is the organ most commonly affected and symptoms of spread here may lead to diagnosis.
What is the most commonly affected site of colorectal cancer metastasis?
The liver is the organ most commonly affected and symptoms of spread here may lead to diagnosis.
Rectal cancers are more commonly associated with … metastasis (prior to … metastasis) due to direct haematogenous spread via the inferior rectal vein and IVC. Other locations of metastatic spread includes the peritoneum brain and bone.
Rectal cancers are more commonly associated with lung metastasis (prior to liver metastasis) due to direct haematogenous spread via the inferior rectal vein and IVC. Other locations of metastatic spread includes the peritoneum brain and bone.
Appendiceal cancers are often considered separately. Most are …, though around 1 in 3 are adenocarcinoma. They may present with symptoms, be incidentally identified on imaging or be found on histology following appendicectomy.
Spread tends to be into the peritoneum. The appearance of pseudomyxoma peritonei (if mucin producing) may be seen.
Appendiceal cancers are often considered separately. Most are carcinoids, though around 1 in 3 are adenocarcinoma. They may present with symptoms, be incidentally identified on imaging or be found on histology following appendicectomy.
Spread tends to be into the peritoneum. The appearance of pseudomyxoma peritonei (if mucin producing) may be seen.
Colorectal cancer may present with … (3)
change in bowel habit, anaemia and weight loss.
Colorectal cancer - how it usually diagnosed?
It is often asymptomatic and diagnosed through screening or incidentally during investigations ordered for other reasons. Diagnosis also frequently follows the recognition of an unexplained (and typically iron deficient) anaemia - a key indication for endoscopy.
Up to 1/3 of CRC cases present with … …
Up to 1/3 of CRC cases present with bowel obstruction.
Symptoms of CRC (6)
Change in bowel habit Weight loss Malaise Tenesmus PR bleeding Abdominal pain
Signs of CRC (3)
Pallor
Abnormal PR exam
Abdominal mass
These are signs and symptoms of what?
Colorectal cancer
Metastatic disease - CRC symptoms
Hepatomegaly
Jaundice
Abdominal pain
Lymphadenopathy
CRC metastatic disease - A whole myriad of features may develop depending on the location of metastasis. Haematogenous spread leads to liver mets as a result of the … system, though rectal disease may drain via the inferior rectal vein to the IVC and result in … deposits. The … and … are also commonly affected.
A whole myriad of features may develop depending on the location of metastasis. Haematogenous spread leads to liver mets as a result of the portal system, though rectal disease may drain via the inferior rectal vein to the IVC and result in lung deposits. The bone and brain are also commonly affected.
Why is the liver the most common site of metastasis from CRC?
The liver is the most common site of metastasis from CRC; this is thought to be due to the venous drainage of the colon and rectum. Approximately 50% of CRC patients will develop liver metastasis during the course of the disease.
Right vs Left CRC - any difference in pattern of growth?
Though lesions throughout the bowel follow the same pathogenesis, the pattern of growth shows some variability.
Lesions arising on the right side of the colon have a tendency to develop as masses arising from a dysplastic polyp. The classical presentation is that of iron-deficiency anaemia.
Lesions arising from the left side of the colon have a tendency to grow circumferentially often creating an ‘apple core’ appearance. This may lead to narrowing of the lumen and symptoms of change in bowel habit and eventual obstruction.
Lesions arising on the right side of the colon have a tendency to develop as masses arising from a dysplastic polyp. The classical presentation is that of …
Lesions arising on the right side of the colon have a tendency to develop as masses arising from a dysplastic polyp. The classical presentation is that of iron-deficiency anaemia.
Lesions arising from the left side of the colon have a tendency to grow circumferentially often creating an ‘… core’ appearance. This may lead to narrowing of the lumen and symptoms of change in … habit and eventual ….
Lesions arising from the left side of the colon have a tendency to grow circumferentially often creating an ‘apple core’ appearance. This may lead to narrowing of the lumen and symptoms of change in bowel habit and eventual obstruction.
