Risk Factors
Colorectal cancer is the fourth most common cancer in the US, with Americans facing a lifetime risk of 6% for this cancer. An estimated 147,000 people in the US are expected to be diagnosed with colon or rectal cancer in 2004.
Sex
The risks overall are equal in men and women, but men have a higher risk for rectal cancers and women for colon cancers.
Age
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The most important risk factor for colon cancer is getting older. More than 90% of these cancers occur in people over 50. The rate of colorectal cancer in patients under 20 years is less than 1 in 100,000 per year. At age 50 about one in 2,000 people per year will develop colorectal cancer, and after age 65, this rate increases to almost 3 in 1,000.
Ethnicity
Compared to Caucasians, African Americans are at higher risk of colon (but not rectal) cancer. The highest risks are in men of African descent, particularly in the sub-Saharan region. Ashkenazi Jews, of Eastern Europe descent, also have a higher incidence of colorectal cancer.
Family History
About 25% of patients under 45 years old and 15% of everyone who develops colorectal cancer have a genetic risk. The average lifetime risk of developing colorectal cancer is approximately 2%. People who have a sibling or parent (first degree relative) who developed colorectal cancer have three times (6%) the lifetime risk of developing colorectal cancer. People who have a first degree relative who developed colorectal cancer before age 45 have an even higher, 10%, lifetime risk of developing colorectal cancer.
Lifestyle Factors
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