Colorectal Cancer Flashcards
What is the peak incidence for colorectal cancer?
65-74 years old
What is the aetiology behind colorectal cancer?
Chromosomal instability pathway in colon cancer
Micro satellite instability pathway in colon cancer
Hypermethylation phenotype pathway in colon cancer
COX-2 overexpression
What are the risk factors for colorectal carcinoma?
Age >40
Hereditary syndrome - familial adenomatous polyposis, hereditary non polyposis colorectal cancer
Associated conditions - colorectal adenomas and serrated polyps. Inflammatory bowel disease. Endocarditis. Diabetes types 2
Lifestyle - smoking, alcohol consumption
Diet - obesity, processed meats, high fat low fibre diet
What are the protective factors against colorectal carcinoma?
Long term use of aspirin and NSAID’s
Physical activity
Diet rich in fibre and verges and lower in meats
What are the constitutional clinical features of colorectal cancer?
Weight loss
Fever
Night sweats
Fatigue
Abdominal discomfort
What are the clinical features of right sided colon carcinomas?
Occult bleeding or melena
Manifestations of iron deficiency anaemia
Diarrhoea
what are the clinical features of left sided colon carcinoma?
Changes in bowel habits
Blood streaked stool
Colicky abdominal pain
What are the clinical features of rectal carcinomas?
Heamatochezia
Decreased stool calibre (pencil shaped)
Rectal pain
Tenesmus
Flatulence
Fecal incompetence
What are the red flags for colorectal cancer?
Melena
Hematochezia
Altered bowel habits
Unexplained weight loss
Unbexplained iron deficiency anaemia, especially in men older than 50 years old and post menopausal women
Which areas can colorectal cancer metastasise?
Liver metastasis - ascites, abdominal distension, hepatomegaly, RUQ pain, jaundice, anorexia, early satiety
Lung metastasis - dyspnoea, cough, hemoptysis, pleural effusion
Peritoneal metastasis - ascites, abdominal distension, diffuse abdominal pain, bowel obstruction
Evidence of distant lymphatic spread - Virchow’s node
Which tests are required for a diagnosis of colorectal cancer?
Initial - digital rectal exam
Flexible sigmoidoscopy with or without anascopy
Complete colonoscopy
Double contrast barium enema
What are the findings of a digital rectal exam (DRE)?
Distal rectal cancers may be palpable
Evidence of blood on DRE
What are the typical findings in a complete colonoscopy?
Ulceroproliferative friable mass
Biopsy is required to confirm the diagnosis
What are the findings in a double contrast barium enema?
Endoluminal filling defect typically with irregular margins
Apple core lesion, sharply defined circumferential narrowing of the bowel caused by a stenosing of CRC
What are the lab tests that should be done for CRC?
CBC - may show microcytic anaemia (iron deficiency anaemia)
Liver chemistries and coagulation - may be abnormal in patients with multiple hepatic metastases
Counselling and genetic testing - for patients <50 with CRC
Carcinoembyonic antigen - obtain baseline levels in all patients before initiating treatment
