- Age: The risk of developing colorectal cancer increases with age. Most cases occur in the 60s and 70s, however whilst only 2.5% of cases of colorectal cancer occur in the under 50's it is on the increase. A significant proportion of young people who are diagnosed with colorectal cancer have no hereditary risk or family history of the disease.
- Polyps of the colon: Adenomatous polyps, have a risk of developing into colon cancer and the risk increases with the size, number and histological appearance of such polyps. The histological appearance of polyps is also an indication of The removal of colon polyps at the time of colonoscopy reduces the risk of subsequent colon cancer.
- History of cancer: Individuals who have previously been diagnosed and treated for colon cancer are at increased risk for developing colon cancer in the future. Women who have had cancer of the ovary, uterus, or breast have a higher than average risk of developing colorectal cancer.
- Family history of colon cancer, especially in a close relative before the age of 55 or if diagnosed in multiple relatives.
- Familial adenomatous polyposis (FAP) if untreated, carries a very high risk of developing colorectal cancer by the age of 40
- Hereditary nonpolyposis colorectal cancer (HNPCC) or Lynch syndrome
- Smoking: Smokers are more likely to die of colorectal cancer than nonsmokers. An American Cancer Society study found "Women who smoked were more than 40% more likely to die from colorectal cancer than women who never had smoked. Male smokers had more than a 30% increase in risk of dying from the disease compared to men who never had smoked.
- Diet: Studies show that a diet high in red meat (particularly proccessed meat) and low in fresh fruit, vegetables, poultry and fish increases the risk of colorectal cancer.
- Physical inactivity: People who are physically active are at lower risk of developing colorectal cancer.
- Inflammatory bowel disease: About one percent of colorectal cancer patients have a history of chronic ulcerative colitis. The risk of developing colorectal cancer varies inversely with the age of onset of the colitis and directly with the extent of colonic involvement and the duration of active disease. Patients with colorectal Crohn's disease have a more than average risk of colorectal cancer, but less than that of patients with ulcerative colitis.
- Environmental factors: Industrialized countries are at a relatively increased risk compared to less developed countries that traditionally had high-fibre/low-fat diets.
Colorectal cancer is a disease which can have no symptoms at all for many years. This is why it is so important to participate in regular colorectal cancer screening.
If symptoms occur, these depend on the location of the tumor in the colon, and whether it has spread elsewhere in the body (metastasis). While no symptom is diagnostic of colorectal cancer, rectal bleeding or anaemia are high risk factors.
Other symptoms can include:
- persistent change in intestinal function over a period of several weeks
- unexplained constipation or diarrhoea
- very dark stools
- unexplained severe pain and/or lump in the abdomen
- extreme fatigue without an obvious cause
It is important to remember that most symptoms do not turn out to be colorectal cancer. However, if you are experiencing any of the above symptoms you should see your doctor.
It is most important to remember that most symptoms do not turn out to be colorectal cancer. However, if you are experiencing any of the above symptoms you should go to see your doctor.