What are risk factors for colon cancer?
A colon cancer or rectal cancer risk factor is any condition that makes a person more likely to develop these diseases (often combined as colorectal cancers). Some of the risk factors like dietary factors can be modifies by people, while some other risk factors like age are not modifiable. Investigators have identified several risk factors that increase a person's chance of developing colorectal cancer. The simple presence of one or more risk factors does not necessarily mean that someone will develop colorectal cancer. Absence of any risk factors does not mean that an individual will not develop it, but generally more risk factors you have higher is the chance of developing colorectal cancer.
Risk factors for colorectal cancer
- Age: Colorectal cancer is more common in people over the age of 50 and the chance of developing colorectal cancer increases as age increases. This doesn't mean that colorectal cancer does not occur at younger age. More than 90% of people who develop colorectal cancer are older than 50 years.
- Diet: The development of colorectal cancer appears to be associated with diets that contain high amount of fat and calories and subsequently is low in fiber. High intake of meat may be associated with colorectal cancer. The exact role of dietary factors in causation of colorectal cancer is not clear at this time. Ongoing research is expected to increase our understanding of this critical issue.
- Large intestinal polyps: Polyps are non-cancerous growths, which may develop on the inner wall of the colon and rectum. This may occur in many people especially after age 50. Polyps may be of different types, and some of these may be associated with increased risk of development of colorectal cancer. In a rare, inherited condition called familial adenomatosis polyposis (FAP), hundreds or even thousands of polyps may develop in the large intestine , causing almost 100 percent risk of developing colorectal cancer in these individuals if left untreated.
- Family history of colon cancer: Close relatives (parents, siblings, children) of colorectal cancer patients are at higher risk of developing this disease. This increased risk is higher if the relative had the cancer at a young age. If several family members have had colorectal cancer, the chances increase even more.
- Medical conditions: Ulcerative colitis is a medical condition in which the inner lining of the colon becomes ulcerated in multiple places. If someone develops ulcerative colitis the chance of developing colorectal cancer is increased. Having this condition increases a person's chance of developing colorectal cancer. Colon cancer risk may also be slightly increase in another disease called Crohn's disease. This disease has some similarity to ulcerative colitis but is more often associated with scarring and obstruction of the intestine than ulceration.
- Personal cancer history: Women with a past history of developing breast cancer, ovarian cancer and uterine cancer may have increased risk of developing colorectal cancer. The risk of developing second colorectal cancer
- Lack of exercise: People who leads sedentary life, with not much of physical activity may have a higher risk of developing colorectal cancer.
- Race and ethnic background: Risk of developing colorectal cancer is higer in Jews of Eastern European descent (Ashkenazi Jews). Recent findings suggest a genetic abnormality in this group of people that is casing an increased risk of developing colorectal cancer.
- Obesity: Overweight by itself may be risk factor for colorectal cancer, the chance of dying from colorectal cancer is higher in obese individuals.
- Diabetes: Diabetes may increase the chance of developing colorectal cancer by as much as 40%.
- Smoking: Smoking may increase the risk of developing colorectal cancer by as much as 40%. Smokers may swallow some of the cancer-causing chemicals and this may be an explanation for the increased risk of colorectal cancer in smokers. Some of these substances are also absorbed into the bloodstream thus causing increased risk of many cancers.
- Alcohol consumption: Heavy alcohol consumption may be associated with increased risk of colorectal cancer. Depletion of body vitamins including folic acid may play in the development of colon cancer but the direct effect of alcohol on the colon may also be responsible for the increased risk.
- Genetic or Family Predisposition: As mentioned above people whose close relatives have had colorectal cancer have a higher risk of developing colorectal cancer. There are many inherited disorders, which may increase a persons risk of developing colorectal cancer. There are mainly two genetic disorders associated with increased risk of colorectal cancer 1. Familial Adenomatosis Polyposis (FAP) 2. Hereditary Non-Polyposis Colorectal Cancer (HNPCC)
- Familial Adenomatous Polyposis: Familial Adenomatous Polyposis. This is a rare type of inherited disorder that may affect 1 in 8000 people. In this genetic disorder, hundreds or even thousands of polyps may develop in the large intestine, causing almost 100 percent risk of developing colorectal cancer in these individuals if left untreated The polyps are not present at birth but develop over time.
- Gardner's Syndrome: This is a subtype of FAP, in which a type of benign tumor called adenoma may affect the entire large and small bowel. These patients may have other associated abnormalities as well which include, desmoid tumors, lipomas and sebaceous cysts.
- Hereditary Non-polyposis Colon Cancer (HNPCC) Syndromes: This is another form of genetic disorder with increase risk of developing colorectal cancer. In this genetic condition there are no increased incidence of polyp development. Patients are included in this diagnosis if there is a history of developing colorectal cancer at an early age in the family. The diagnosis can only be confirmed by genetic testing. The following are the clinical criteria for diagnosing HNPCC. These are called the Amsterdam criteria
- At least one family member who has developed colorectal cancer by age 50.
- Colorectal cancer involving at least two successive generations.
- Proven colorectal cancer in three or more relatives, one of whom is a first degree relative of the other two.