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colorectal cancer (bowel cancer)

risk factors

  • chronic inflammation:
  • genetics:
    • familial adenomatous polyposis (FAP) and hereditary non-polyposis colorectal cancer (HNPCC)
      • account for 5% of colorectal cancers
      • almost all FAP patients develop bowel cancer by age 40
      • 9 in 10 males and 7 in 10 females with HNPCC develop bowel cancer by age 70
    • other genetic syndromes:
      • account for 20% of colorectal cancers
      • first-degree relative with colorectal cancer ⇒ 2x risk colorectal cancer and 70% higher risk of adenoma
      • BRCA1 mutations may account for some of this excess familial risk, particularly in younger women
      • 3 gene alleles appear to have increased risk of 1.18 per allele per quartile of average processed meat intake 1)
      • tall people:
        • it appears that for every 5cm increase in height, colon cancer risk is 11% higher in females and 9% higher in males, and rectum/anus cancer risk is 9% higher in females and 6% higher in males
  • diet:
    • processed meat (see above)
    • red meat:
      • 17-30% increased risk if eat 100-120g/day red meat
    • low fibre diet:
      • risk appears to be reduced by 10% for every 10g/day total dietary fibre and cereal fibre
    • possible risk factors:
      • eggs:
        • risk may be 29% higher in people with the highest egg consumption, compared with those with the lowest
      • low non-starch vegetable/fruit diet:
        • risk appears to be 2% lower per 100g/day of vegetables consumed
        • risk appears to be 11% lower in those with the highest intake of fruits compared with those with the lowest intake
      • low milk diet or low calcium diet:
        • risk appears to be 9-15% lower per 200-250g/day of milk consumed
        • however, calcium and Vit D supplements effect on risk is unclear
      • low folate diet:
        • 31% reduction in bowel cancer risk for people with the highest overall folate intake 12-16 years before diagnosis, but no effect of intakes in the more recent past
    • risk appears to be 33% higher in people who are obese by BMI compared to normal BMI
    • risk of colorectal adenoma is 47% higher in people who are obese by BMI
    • type II diabetes have 22-30% increased risk of bowel cancer, compared with non-diabetics
    • metformin is associated with an 11-36% decrease in bowel cancer risk
    • insulin is associated with a 37-61% increased risk
    • the most physically active people have 14-30% lower risk of colon cancer, compared with those least physically active
    • risk is 21% higher in people who drink 1.6-6.2 alcohol units per day, compared with non-/occasional drinkers
    • risk is 52% higher in those who consume 6.2 units or more per day, compared with non-/occasional drinkers
    • risk increases by 7% per unit of alcohol consumed per day
    • risk is 20-21% higher in current cigarette smokers compared with never-smokers
    • risk is 17-25% higher in former cigarette smokers compared with never smokers
    • risk increases with the number of cigarettes smoked per day, by 7-11% per 10 cigarettes per day
    • 10x risk of colorectal cancer
    • 90% of anal cancers are linked to HPV infection
    • H.pylori infection increases risk by 39%
    • accounts for 1% of colorectal cancers in Western society
neo_colorectal.txt · Last modified: 2022/05/24 07:26 by gary1

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