Most colon cancer is on the left side of the sigmoid colon, the segment nearest the rectum. In United States, colon cancer is one of the most common causes of death from cancer.
What Causes Colon Cancer?
The cause of colon cancer is unknown. How diet promotes cancer is not known either, but some researchers believe it plays an important role and studies have found that people who consume a diet low in fibre and high in protein and fat have a high incidence of colon cancer.
It may well be related to the digestion of fats and to the speed at which faeces travel through the bowel. Fresh fruit and vegetables may act as protective factors.
Colon cancer often develops from a benign mass (adenoma) that grows from the surface fo the bowel and then spreads into the bowel channel. Adenomas range in size from the barely visible to several centimetres wide.
Cancer cells may grow inside them and the larger the adenoma is, the more likely it is to contain them. A small colon cancer can lie undetected for many years, without causing any symptoms.
The growth patterns and eventual symptoms all differ, depending on where the cancer is located along the colon. Eventually, if it is not treated, it can spread to other body organs with fatal consequences.
What Are The Symptoms of Colon Cancer?
- Persistent change in bowel habits (either diarrhoea or constipation)
- Rectal bleeding
- Lower abdominal pain or bloating
- Change in the size or shape of the stool
- Weight loss
How is Colon Cancer Diagnosed?
A biopsy of sample tissue taken from a tumour, lesion or other suspicious area may be removed for further examination to establish a diagnosis of colon cancer. Such investigations might include a barium enema, a sigmoidoscopy or a colonoscopy.
A barium enema involves infusing a chalky substance into the rectum, in order to outline the colon on an X-ray.
With a sigmoidoscopy, a short flexible tube is inserted for a colonoscopy, which allows the colon to be examined along its entire length Some tissue samples may also be removed for analysis during this procedure.
Colon cancer is treated by surgical removal of the tumour, along with a portion of the colon above and below the cancer, to make sure that all of it is removed.
The lymphatic tissue that drains the area is also removed and studied for any signs of possible spread.
Usually the two ends of the colon are rejoined and will function normally after surgery. Occasionally a colostomy (an opening between the colon and the surface of the body which allows faecal matter to be evacuated from the colon) may be necessary.
This is often just a temporary measure in order to allow healing of the bowel area where the tumour has been removed.
When Should I See My Doctor?
You should see your doctor as soon as possible if you notice any warning symptoms of colon cancer. As the likelihood of colon cancer increases with age, some doctors recommend that people over 50 years of age, especially high-risk individuals should have a sigmoidoscopy (when the rectum and colon are examined with a flexible viewing tube) every three to five years.
What Will The Doctor Do?
Your doctor will probably carry out a physical examination and arrange for any further tests or X-rays. You may be referred to a hospital for these to be carried out.
What Can I Do Myself?
The Most Unexceptional thing that you can do if you have any symptoms of possible colon cancer is to see your doctor as soon as possible. Colon cancer is curable if it is diagnosed and treated early enough.
Unfortunately many people put off seeing their doctors until the cancer is at an advanced stage, which makes a cure more difficult to achieve.
Is Colon Cancer Dangerous? Maybe, but Most Likely Not.
Although colon cancer is a dangerous condition, over half of those treated surgically survive for more than five years after operation. The earlier the cancer is diagnosed and treated, the better the chances are there for a cure.
Who Has Higher Risk Of Developing Colon Cancer?
Some people have an increased risk of developing colon cancer. These risk factors include:
- family history of the disease
- polyps in the colon
- ulcerative coligtis and other inflammatory bowel diseases
If you fall into a high risk group you should see your doctor for advice about regular screening tests.
Treatments for Colon Cancer
Radiation therapy may be used either before or after surgery, and cancer chemotherapy may be given after surgery, depending upon how far the cancer has spread.