The colon and rectum (Colon Cancer)
The colon and rectum are parts of the digestive system. They form a long, muscular tube called the large intestine. The colon is the first five feet of the large intestine, and the rectum is the last six inches.
Partly digested food enters the colon from the small intestine. The colon removes water and nutrients and turns the rest into waste (stool). The waste passes from the colon into the rectum and then out of the body through the anus .
Cancer begins in cells, the building blocks that make up tissues. Tissues make up the organs of the body. Normally, cells grow and divide to form new cells as the body needs them. Sometimes, this orderly process goes wrong. New cells form when the body does not need them, and old cells do not die when they should. These extra cells can form a massive tissue called a tumour.
Tumours can be benign or malignant.
Benign tumours are not cancer. Benign tumours are rarely life threatening.
Most benign tumours can be removed. If left however they can develop into malignant tumours. Benign tumours do not invade the tissues around them.
Malignant tumours are cancer. Malignant tumours may be life threatening.
Malignant tumours can invade and damage nearby tissues. They may spread by entering the blood stream or the lymphatic system. This spread of cancer is called metastasis.
When colorectal cancer spreads outside the bowel, cancer cells are often found in nearby lymph nodes. Colorectal cancer cells most often spread to the liver.
Research has shown that people with certain risk factors are more likely than others to develop colorectal cancer.
Studies have found the following risk factors for colorectal cancer;
- Age over 50
Colorectal cancer is most likely to occur as people get older. More than 90% of people with this disease are diagnosed after the age of 50.
- Colorectal polyps
Polyps are growths on the inner wall of the colon or rectum. Most polyps are benign; some polyps (adenomas) can become cancer. Finding and removing adenomas will reduce the risk of colorectal cancer.
- Family history of colorectal cancer
Close relatives (parents, brothers, sisters or children) of a person with a history of colorectal cancer are more likely to develop this disease themselves especially if the relative had the cancer at a young age. Patients who have more than one close relative with colorectal cancer has an even greater risk of getting the disease.
- Genetic alterations
Changes in certain genes increases the risk of colorectal cancer.
- Hereditary non-polyposis colon cancer (HNPCC)
This is the most common type of inherited colorectal cancer. It accounts for about 2% of colorectal cancer cases. It is caused by changes in an HNPCC gene. Most people with an altered HNPCC gene develop colon cancer. The average age of diagnosis of colon cancer is 40 years of age.
- Familial polyposis (FAP)
This is a rare, inherited condition in which hundreds of polyps form in the colon and rectum. It is caused by a change in a specific gene called APC. Unless FAP it is treated it will almost always lead to colorectal cancer by the age of 40. FAP accounts for less than 1% of colorectal cancers.
- Family members of people who have HNPCC or FAP
Family members of people who have HNPCC or FAP will be recommended to have genetic testing to check for specific genetic changes. For those who have changes in their gene, your doctor may suggest ways to try and reduce the risk of colorectal cancer, or to improve the detection of this disease. For adults with FAP, the doctor may recommend an operation to remove all or part of the colon and rectum.
- Personal history of cancer
A person who has already had colorectal cancer may develop colorectal cancer a second time. Women with a history of cancer of the ovary, uterus or breast are just somewhat at higher risk of developing colorectal cancer.
- Ulcerative colitis or Crohn's disease
A person who has had a condition that causes inflammation of the colon such as ulcerative colitis or Crohn's disease for many years is at increased risk of developing colorectal cancer.
Studies suggest that diet high in fat (especially animal fat) and low in calcium, folate and fibre may increase the risk of colorectal cancer. Some studies also show that people who eat a diet very low in fruits and vegetables may have a higher risk of developing colorectal cancer.
- Cigarette smoking
A person who smokes cigarettes may be at increase risk of developing of polyps and colorectal cancer.
Screening tests can help your doctor find polyps or cancer before you have symptoms. Finding and removing polyps has been shown to reduce the risk of patients developing colorectal cancer. Treatment for colorectal cancer is more likely to be effective when disease is found early.
- To find polyps or colorectal cancer
People in the 50s and older should be screened.
People who have a higher than average risk of colorectal cancer may need to undergo screening tests before the age of 50.
The following screening tests can be used to detect polyps, cancer or other abnormal areas;
This is the gold standard for the investigation of the colon and rectum. Using this examination your doctor examines inside the rectum and the entire left colon using a long lighted tube called a colonoscope. Polyps and biopsies may be found and these can be removed during this examination. If polyps are found the polyps will be removed. This procedure is called a polypectomy.
Left sided colonoscopy
With this examination your doctor examines inside your rectum and in the lower part of your colon with a lighted tube called a colonoscope.
Faecal occult blood test
Sometimes cancers or polyps bleed and the faecal occult blood can detect tiny amounts of blood in the stool. If this detects blood, other tests are needed to find the source of the blood. Benign conditions such as haemorrhoids can also cause blood in the stool and obviously using this method polyps and cancers that do not bleed will not be detected.
Digital rectal exam
Rectal exam is often part of a routine physical examination. Your doctor inserts a lubricated, gloved finger into your rectum to feel for abnormal areas.
This is also an excellent method of detecting polyps, however it may well miss polyps smaller than 5mm and unfortunately with this investigation the polyps cannot be removed.
You may find it helpful to read NCI fact sheet on colorectal cancer screening.
The common symptom of colorectal cancer is a change in bowel habit.
- Having diarrhoea or constipation
- Feeling like your bowel does not empty completely
- Finding blood (either or bright red or dark) in your stool
- Finding your stools are narrower than usual
- Frequently having gas pains or cramps, or feeling full or bloated
- Losing weight with no known reason
- Feeling very tired all the time
- Having nausea or vomiting
Most often, these symptoms are not always due to cancer. Other health problems can cause the same symptoms. Anyone with these symptoms should see a doctor to be diagnosed and treated as early as possible.
Usually, early cancer does not cause pain. It is important not to wait to feel pain before seeing a doctor.
You will require a physical examination.
You may well undergo a colonoscopy. If tests show an abnormal area (such as a polyp) a biopsy to check for cancer cells may be necessary.
You may want to ask your doctor the following questions before having a biopsy
Q. How will the biopsy be done?
A. The biopsy will be done via the colonoscope and you will not feel it.
Q. Will I have to go to the hospital for the biopsy?
A. No. This investigation, i.e the colonoscopy will be done in the rooms.
Q. How long will it take?
A. Colonoscopy usually takes approximately 30 to 40 minutes.
Q. Will I be awake? Will it hurt?
A. You will under what is called conscious sedation and the biopsy will not hurt.
Q. Are there any risks? What are the chances of infection or bleeding after the biopsy?
A. The risks are extremely small and it is almost unheard of to have any infection following a biopsy, equally bleeding is extremely unusual.
Q. How soon will I know the results?
A. Normally we will get the results after a period of 48 hours.
For further information on treatment, nutrition and physical activity, rehabilitation, follow-up care, complimentary please contact Dr Michael Elliot.