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Questions and Answers
What is the most common cellular origin of colorectal tumors?
What is the most common cellular origin of colorectal tumors?
A mutation in which gene is most often associated with the development of adenomatous polyps?
A mutation in which gene is most often associated with the development of adenomatous polyps?
In the early stages of colorectal cancer, what is the most typical clinical presentation?
In the early stages of colorectal cancer, what is the most typical clinical presentation?
What type of blood loss is most likely to be associated with tumors in the ascending colon?
What type of blood loss is most likely to be associated with tumors in the ascending colon?
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Which of the following is NOT a typical diagnostic test for colorectal cancer?
Which of the following is NOT a typical diagnostic test for colorectal cancer?
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Which of the following symptoms is most often linked to colorectal cancer?
Which of the following symptoms is most often linked to colorectal cancer?
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What does the abbreviation 'FIT' stand for in the context of diagnostic criteria for colorectal cancer?
What does the abbreviation 'FIT' stand for in the context of diagnostic criteria for colorectal cancer?
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Which of the following is NOT a typical cause of colorectal cancer?
Which of the following is NOT a typical cause of colorectal cancer?
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Study Notes
Colorectal Cancer Overview
- Colorectal cancer is the second most common cancer in Australia.
- It causes 5336 deaths annually in Australia.
- It can develop anywhere in the large intestines.
- 90% of cases are diagnosed in adults over 50.
- Tumours are typically of epithelial origin.
- Benign tumours are called adenomas.
- Malignant tumours are called adenocarcinomas.
Colorectal Cancer Pathophysiology
- The diagram shows a breakdown of the disease process associated with colorectal cancer:
- Pathophysiology
- Clinical manifestations
- Diagnostic criteria
- Treatment
Colorectal Cancer Location
- Cancer can develop in various parts of the colon and rectum.
- Some common locations and percentages are provided in a chart:
- Right side: (hepatic flexure 3%, ascending colon 8%, caecum 14%, appendix 1%)
- Transverse colon 5%
- Left side: (splenic flexure 2%, descending colon 3%, sigmoid colon 20%, rectosigmoid junction 7%, rectum 27%).
- Other/ unspecified sites account for 8%.
Colorectal Cancer Development
- Colorectal cancer development involves a series of stages, often starting with harmless polyps evolving into potentially malignant adenomatous polyps eventually becoming cancerous.
- Risk factors are shown including family history, familial adenomatous polyposis, inflammatory bowel disease, smoking, obesity, alcohol consumption, red meat intake, type 2 diabetes, high-fat diet, and low-fiber diet.
- Protective factors include a diet rich in cereals, vegetables, milk, fish, folic acid, calcium, vitamin D, magnesium, and selenium, postmenopausal estrogen use, physical activity, and NSAID use.
Colorectal Cancer Causes
- Two pathways lead to colorectal carcinoma development:
- Chromosomal instability (85%): Loss of tumour suppressor ability & Impaired DNA repair.
- Replication errors (15%): Defects in DNA repair mechanisms. Genetic mutations are involved, specifically mutations in the APC (adenomatous polyposis coli) tumour suppressor gene and associated replication errors.
Colorectal Cancer Clinical Manifestations
- Early stages are often asymptomatic.
- Symptoms can include:
- Enlarged tumours leading to ulceration and haemorrhage.
- Occult blood in stools.
- Tumors in the ascending colon can cause occult blood in stools. Tumors in the descending colon or rectum can result in frank blood in stools.
- Abdominal pain
- Bowel obstruction
- Anemia from blood loss in the stool.
- Changes in bowel habits.
- Paraneoplastic manifestations.
Colorectal Cancer Diagnostic Criteria
- Diagnostic tools include:
- History taking and physical examination.
- Blood tests (including RBC count).
- Faecal immunochemical tests (FIT).
- Colonoscopy.
- Barium enemas.
- CT or MRI scans.
- PET scans.
- Ultrasound.
Colorectal Cancer Staging
- Staging (ACPS) is used to categorize colorectal cancer based on tumour depth and spread:
- Stage I: tumours in the bowel lining.
- Stage II: tumours spread deeper into the bowel walls.
- Stage III: cancer spreads to nearby lymph nodes.
- Stage IV: tumours spread beyond the bowel to other organs (e.g., liver, lungs) and lymph nodes (advanced, potentially metastatic disease).
Colorectal Cancer Treatment
- Treatment depends on the stage of the disease.
- Treatment options may include surgery, chemotherapy, radiation, and targeted biological therapies.
- Survival rates (5-year relative survival) vary by stage, highlighting the importance of early detection.
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Description
This quiz covers essential information about colorectal cancer, including its prevalence, mortality rates, and the age at which it is typically diagnosed. It explores the disease's pathophysiology, clinical manifestations, and common sites of occurrence within the colon and rectum. Test your knowledge on this critical health topic.
