Colon Cancer Risk Factors
Prevalence of colon cancer is more in developed countries, more so in the obese population. And migration to the developed countries also increases the risk of the disease.
But for the past few years, the incidence of colon cancer is decreasing in USA and Canada, whereas it is increasing in China and Japan. Moreover, it’s incidence in the population more than 50 years of age is going down, whereas, it is increasing in young population less than 50 years of age.
- Risk of developing colorectal cancer almost doubles in an individual with a history of colorectal cancer in first-degree relatives (parents, brother, sister, or child).
- The risk further increases several folds for such individuals if the first-degree relative gets diagnosed with the disease at an age </=60 years.
Following are some examples:
- Lynch syndrome or hereditary non-polyposis colorectal cancer
- Familial adenomatous polyposis (FAP)
- Peutz-Jeghers syndrome
- Juvenile polyposis
Inflammatory Bowel Disease
- Individuals with a history of colorectal cancer, adenomatous polyps, inflammatory bowel disease (ulcerative colitis or Crohn’s disease) are generally at higher risk of developing colorectal cancer.
- Ulcerative colitis carries a risk of colorectal carcinoma 30 times greater than general population.
- Risk increases with duration of disease.
- After 30 years, risk increases to 35%.
- Crohn’s disease associated with 10-20 fold increased risk of cancer.
- Need to do surveillance in these population.
Most cases of colorectal cancer risk factors develop from non-cancerous adenomatous polyps through a process called adenoma-carcinoma sequence.
- Older age individuals are generally at increased risk of developing colorectal cancer.
- Older age is also associated with high-grade dysplasia within an adenoma, independent of size and histology.
- Tobacco/cigarette smoking, excess alcohol consumption, and
- low physical activity have been reported to increase the risk of developing colorectal cancer.
- Cigarette smoking- More than 20 pack years increases the risk of large adenoma, and more than 35 pack years increases cancer risk.
- Obesity, diabetes mellitus (especially type 2 diabetes), high waist girth are some other risk factors for colorectal cancer.
- Consumption of red and processed meat, high-calorie diet, animal fat; and low intake of fruits and vegetables, fish, legumes, dietary fibers, and vitamins have been implicated to elevate the risk of colorectal cancer.
- Alcohol consumption increases risk
- No clear cut risk with coffee or tea
- Use of certain drugs like aspirin, other nonsteroidal anti-inflammatory drugs (NSAID), hormone replacement therapy, and COX-2 inhibitors have been reported to decrease the incidence of colorectal cancer.
- Folate is protective.
- Calcium supplementation decrease new adenomas.