What're the risk factors for colorectal cancer?
Certain factors increase a person's risk of developing the disease. These include:
Family history of colon cancer, especially in a close relative before the age of 55 or multiple relatives. Hereditary nonpolyposis colorectal cancer (HNPCC) is a group of diseases that tend to be more common in certain families.
Members of these families have a higher risk of developing colorectal cancer. There are two types of HNPCC, designated as A and B. HNPCC type A is associated with colon tumors only, and is more likely to involve the right side of the colon. HNPCC type B occurs in association with other cancers, such as those of the breast, stomach, kidney, ovaries, and uterus.
Age. The risk of developing colorectal cancer increases with age. Most cases occur in the 60's and 70's, while cases before age 50 are uncommon unless a family history of early colon cancer is present.
History of cancer. Women who have had cancer of the ovary, uterus, or breast are at higher risk of developing colorectal cancer.
Familial adenomatous polyposis (FAP) carries a near 100% risk of developing cancer of the colon if untreated.
Long-standing ulcerative colitis or Crohn's disease of the colon, approximately 30% after 25 years if the entire colon is involved. The risk is greater for those with ulcerative colitis than for those with Crohn's disease, and it is directly related to how widespread and severe the disease is in a particular individual. Increasing the risk even more is how long an individual has had ulcerative colitis. Individuals who have had ulcerative colitis for 30 or more years have more than a 30% risk of developing colorectal cancer. Areas of the colon affected by colitis often give rise to dysplastic cells (abnormally developed), and from these arise cancer cells.
Smoking. Smokers are more likely to die of colorectal cancer than non-smokers.
Diet. Some studies have shown that people who have diets high in fresh fruit and vegetables and low in red meat are at reduced risk of colorectal cancer.
Virus. Exposure to some viruses (such as human papilloma virus) may be associated with colorectal cancer.
Physical inactivity. People who are physically active are at lower risk of developing colorectal cancer.
Men tend to get colorectal cancer at an earlier age than women, but women live longer so they 'catch up' with men and thus the total number of cases in men and women is equal.