Podcast
Questions and Answers
What is the approximate risk of colorectal cancer associated with untreated colonic polyps after 20 years?
What is the approximate risk of colorectal cancer associated with untreated colonic polyps after 20 years?
Which of the following races has the highest risk of colorectal cancer related mortality?
Which of the following races has the highest risk of colorectal cancer related mortality?
Which among the following age groups has the highest risk of colorectal cancer diagnosis?
Which among the following age groups has the highest risk of colorectal cancer diagnosis?
What percentage of all new colorectal cancer cases annually is accounted for by Inflammatory Bowel Disease (IBD)?
What percentage of all new colorectal cancer cases annually is accounted for by Inflammatory Bowel Disease (IBD)?
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In patients diagnosed with Ulcerative Colitis (UC), how does cancer risk change over 30 years post-diagnosis?
In patients diagnosed with Ulcerative Colitis (UC), how does cancer risk change over 30 years post-diagnosis?
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What is the association between smoking and colorectal cancer?
What is the association between smoking and colorectal cancer?
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Which mutation is commonly associated with smoking-related colorectal cancer?
Which mutation is commonly associated with smoking-related colorectal cancer?
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What is the relationship between sedentary lifestyles and colon cancer risk?
What is the relationship between sedentary lifestyles and colon cancer risk?
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What is the effect of obesity on colon cancer risk in men compared to normal weight?
What is the effect of obesity on colon cancer risk in men compared to normal weight?
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What is the recommended amount of moderate physical activity for reducing colorectal cancer risk?
What is the recommended amount of moderate physical activity for reducing colorectal cancer risk?
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Study Notes
Colorectal Cancer Epidemiology
- Commonality: Fourth most common cancer in the USA, second most common cause of cancer death. Overall incidence declining.
- Age: 90% diagnosed after 50. Highest risk is 50-54 years, with approximately 7x higher risk than 20-24 year olds.
- Race: Higher incidence and mortality in African Americans (especially non-Hispanic Blacks).
- Sex: About 30% higher incidence and 44% higher mortality in men than in women.
- Socioeconomic Status: Lower socioeconomic status associated with higher colorectal cancer risk.
- Prior Polyps: 24% chance of malignancy in untreated polyps over 20 years. Early polypectomy associated with 80-90% lower incidence.
- Prior Colon Cancer: 3% five-year risk of recurrence after resection.
- Inflammatory Bowel Disease (IBD): ~1% of new CRC cases annually. 2-4 times higher risk in IBD patients. Incidence in IBD population decreasing. IBD also linked to inflammatory polyps. Typically diagnosed 15-20 years after IBD onset. Patients with IBD diagnosed before 30 have a higher risk. Colorectal cancer accounts for 10% all-cause mortality in ulcerative colitis (UC) and 15% in Crohn's disease.
Ulcerative Colitis (UC) - Specific Risk
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Duration: Cancer risk increases with disease duration.
- 2% risk at 10 years.
- 10% at 20 years.
- 20% at 30 years.
- Pattern: Pancolitis highest risk pattern.
- Associated Conditions: Higher risk, especially in the right colon if primary sclerosing cholangitis is present.
- Site: Most common cancer sites are sigmoid colon and rectum.
- Mortality: UC-associated CRC accounts for ~10% of all-cause mortality in UC.
- Molecular Differences: UC-associated CRC more frequent CIMP, earlier TP53 mutations, and less MSI and KRAS.
Crohn's Disease - Specific Risk
- Risk Factors: Risk related to location, extent, and duration of the disease.
- Severity: Isolated colon involvement has 7x greater risk. Ileal and colon involvement has 3x greater risk. Isolated ileal involvement lowest risk pattern. Left-sided colitis associated with higher risk than right-sided colitis.
- Mortality: Crohn's disease-associated CRC accounts for ~15% of all-cause mortality.
Other Risk Factors
- Smoking: 12% of CRC associated with smoking. Smoking linked to BRAF mutations, high MSI, and CIMP. 60% increased risk in smokers (vs. non-smokers). 60% increased risk correlates with 29 pack-years of smoking. Left-sided colon cancer more common in male smokers; right-sided in female smokers. Poorer prognosis in active smokers.
- Alcohol: 13% of CRC associated with alcohol use. >24g/day consumption linked to 25% increased risk; >50g/day to 50% increased risk. More common in males (due to mean alcohol consumption).
- Meat Consumption: Red meat and processed meats linked to increased risk. Mechanisms may include alkylating damage and KRAS mutations. 20% increased risk per 50g/day of processed meat; 10% per 100g/day red meat.
- Diabetes Mellitus: ~38% increased risk of colon cancer diagnosis, ~20% increased risk of colon cancer mortality. Possible link to liver/lymph node metastases. Metformin linked to decreased risk and better outcomes.
- Exercise: Sedentary lifestyle associated with 25-50% greater risk. Long-term physical activity linked to decreased colon cancer risk, but not rectal cancer. Lifestyle change after diagnosis linked to 40% reduced death risk. 150-300 minutes of moderate or 75-150 minutes of vigorous activity recommended.
- Metabolic Syndrome: Associated with early onset (<50) of colon cancer, especially linked to obesity. Increased incidence and mortality in both men and women.
- Obesity: Males with obesity have 50% greater risk of colon cancer; 25% greater risk of rectal cancer. Females with obesity have 10% higher risk of colon cancer, no effect on rectal cancer risk. Higher waist-to-hip ratio is an independent risk factor.
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Description
Test your knowledge on the epidemiology of colorectal cancer, including incidence rates, risk factors, and demographic distributions. This quiz covers key statistics and research findings relevant to colorectal cancer in the USA. Understand the impact of age, race, sex, and socioeconomic status on cancer prevalence and outcomes.
