Colorectal cancer is the third most common type of non-skin cancer in both men (after prostate cancer and lung cancer) and women (after breast cancer and lung cancer). It is the second leading cause of cancer death in the United States after lung cancer. Although the rate of new colorectal cancer cases and deaths is decreasing in this country, more than 145,000 new cases were diagnosed and more than 49,000 people died from this disease each year over the past 5 years.
The exact causes of colorectal cancer are not known. However, studies have shown that certain factors are linked to an increased chance of developing this disease, including the following:
Colorectal cancer is more likely to occur as people get older. Although this disease can occur at any age, most people who develop colorectal cancer are over age 50.
Polyps are abnormal growths that protrude from the inner wall of the colon or rectum. They are relatively common in people over age 50. Detecting and removing these growths may help prevent colorectal cancer.
A person who has already had colorectal cancer is at an increased risk of developing colorectal cancer a second time. Some women with a history of ovarian, uterine, or breast cancer have a higher than average chance of developing colorectal cancer.
Close relatives (parents, siblings, or children) of a person who has had colorectal cancer are somewhat more likely to develop this type of cancer themselves, especially if the family member developed the cancer at a young age.
People who have ulcerative colitis or Crohn’s colitis are more likely to develop colorectal cancer than people who do not have these conditions.
Some evidence suggests that the development of colorectal cancer may be associated with high dietary consumption of red and processed meats and low consumption of whole grains, fruits, and vegetables.
Some evidence suggests that obesity and a sedentary lifestyle is associated with an increased risk of developing colorectal cancer.
Increasing evidence from epidemiologic studies suggests that cigarette smoking, particularly long-term smoking, increases the risk of colorectal cancer.
Screening is checking for health problems before they cause symptoms. Colorectal cancer screening can detect cancer, polyps, nonpolypoid lesions,(flat or slightly depressed areas of abnormal cell growth) and other conditions. Flat or depressed lesions occur less often than polyps, but they may have a greater potential to develop into colorectal cancer. Finding and removing polyps or other areas of abnormal cell growth is the most effective way to prevent colorectal cancer. Colorectal cancer (like most cancers) is generally more treatable when it is found early.
You should talk to your doctor about when to begin screening for colorectal cancer, which test to have, the benefits and risks of each test(s), and the frequency of testing.