Bowel cancer can occur in any part of the large bowel (the colon or rectum) and very rarely in the small bowel. The bowel is the tube of muscle, about four feet long, which runs from the stomach to the rectum. Bowel cancer is one of the most curable cancers if caught early enough.
Most bowel cancers start with warty-like growths, known as polyps, on the inside wall of the gut. Polyps are more common with age but most polyps do not turn to cancer. If potentially cancerous polyps can be found at an early stage, they can be removed painlessly without the need for an operation. If left untreated the cancer in the bowel will increase in size and protrude into the structure of the bowel. There, it may cause a blockage or ulcerate, leading to blood loss and iron deficiency.
Secondary or metastatic bowel cancer is when the cancer has spread through the wall of the bowel to other sites in the body. The cancer may spread to nearby organs such as the liver, via the blood stream or the lymphatic system.
More than 80% of bowel cancer cases arise in people who are 60 years or older.
An unhealthy high fat, low fibre diet with a low intake of fruit and vegetables can increase the risk of bowel cancer. Eating a large amount of red and processed meat can also increase the risk.
Having a first-degree relative who has had bowel cancer almost doubles the risk of developing the disease. There is also a higher risk of bowel cancer if there have been two or more older close relatives from the same side of the family with bowel cancer.
High alcohol consumption and lack of physical exercise can increase the risk of bowel cancer.
Some studies have shown that being obese can significantly increase the chances of developing bowel cancer. A diet that is high in fat and red meat, and low in fibre, fruit and vegetables, can increase the risk of bowel cancer. Maintaining a healthy weight can help to combat bowel cancer.
Long time sufferers of Crohn's disease have a slightly increased risk of bowel cancer. Crohn's disease is a painful inflammation of the gut typified by symptoms such as abdominal pain and diarrhoea. There may also be rectal bleeding, weight loss, and fever. The cause is unknown and may be life-long. Several drugs are helpful in controlling Crohn's disease, but at this time there is no cure.
People who have suffered from ulcerative colitis continuously for more than 20 years have a 30% risk of developing bowel cancer. Colitis is a condition where the bowel becomes red and inflamed. It tends to come and go and can last for a lifetime. The symptoms are bleeding, mucus in the stool and sometimes pain (perhaps after going to the toilet).
Taking HRT or the contraceptive pill appears reduce the risk of women contracting bowel cancer. Female hormones may protect against bowel cancer because they reduce the concentration of bile acids in the colon.
Prevention
Diet
A healthy balanced diet is the most effective way to help prevent bowel cancer. A balanced diet should be high in fibre and low in fat, salt and added sugars. It should contain plenty of fruit, vegetables and starchy foods such as rice, pasta, potatoes and moderate amounts of milk, dairy foods and meat.
There is increasing evidence that eating at least 5 portions of fruit and vegetables a day could lead to a reduction in the number of bowel cancer cases. It is thought up to 80% of cases of bowel cancer may be preventable by changes in diet.
Fruit and vegetables contain a wide variety of substances known to have health benefits including carotenoids, vitamin C, vitamin E and dietary fibre. They also contain many complex plant components, such as flavonoids. The vitamins and plant components contain antioxidants that can destroy harmful free radicals in the body and protect against cancer.
Fruit and vegetables can be consumed fresh, frozen, chilled, canned, dried as well as in juice form. The body will derive vitamins and minerals from all these sources.
Exercise
There has been a lot of research to suggest that exercise can help to prevent against bowel cancer. One recent study showed that regular exercise could cut the risk of developing bowel cancer by almost 50%. To help reduce the risk of cancer, physical activity should be of at least moderate intensity, for approximately 30 minutes, three times a week.
Vitamins / dietary supplements
Taking vitamins or dietary supplements does not appear to have the same beneficial effects as eating fruit and vegetables. It is the interaction between the components in fruit and vegetables not just the vitamins and minerals themselves that help to protect the body. In some studies, supplements caused more harm than good.
Diagnosis
Initial Diagnosis
Rectal examinations
A rectal examination, may be carried out at the first visit to the doctors if there is a suspicion of bowel cancer. The examination also know as a 'PR' is a painless examination with a gloved finger to feel for any suspicious lumps in the bottom or rectum, which might be cancer.
Blood test
A blood test can be taken to see if the patient has anaemia, which could be a sign of bowel cancer. If the doctor feels that there should be further investigation for bowel cancer, a referral to a hospital consultant will be made.
Further Diagnosis
Rigid sigmoidoscopy
This enables the doctor to look inside the rectum through a tube, like a thin, short telescope, passed into the back passage.
Flexible sigmoidoscopy
A thin flexible tube, with a camera or light on the end enables the doctor to look inside the first 60cms of the bowel. A small enema is given first to empty the bowels.
Colonoscopy
A colonoscope is a longer version of the sigmoidoscope. It is a long flexible tube that can look inside the whole bowel. During the test, photographs and biopsies of the cells on the inside of the large bowel can be taken. Laxatives are taken beforehand to clear out the bowel. This is a more in depth procedure than the sigmoidoscope.
Barium enema
A special X-ray examination. The enema, a mixture of barium (a thick white liquid which shows up on x-ray) and air is passed into the back passage through a tube. Any abnormal areas show up black against the white liquid. Laxatives are taken beforehand to clear out the bowel.
MRI (Magnetic Resonance Imaging)
MRI uses magnetic fields to create images of the body. During an MRI the body is moved in and out of a narrow tube as the machine creates images of the body. MRI can be used to look at the bowel and surrounding areas in more detail.
CT scan (computed tomography)
A CT scan uses x-rays to take many pictures of the body that are then combined by a computer to give a detailed picture. A CT scan can often show if the cancer has spread to the liver, lungs, or other organs. CT scans can also be used to help guide a biopsy needle into a tumour. A contrast "dye" may be injected or a special drink used to help outline the area being viewed.
A new way to use a CT scan is to do a 'virtual colonscopy.' After cleaning the stool from the colon and filling the colon with air, a computer assisted reconstruction of the colon from CT images is possible. If anything abnormal is seen, a follow-up colonoscopy will be needed.
Ultrasound
Ultrasound uses sound waves to produce a picture of the inside of the body. Two types of ultrasound might be used for people with bowel cancer. In one, the instrument that gives off sound waves is placed into the rectum. In the other test, used during surgery, the instrument is placed against the surface of the liver to see if the cancer has spread there.
Treatment
Tests are carried out to determine the size of the cancer tumour, its position and whether it has spread. This process is known as 'staging'. At the operation what is known as Duke's staging is carried out based on the surgeons and pathologists reports.
Surgery
Surgery is the main treatment for removing the cancer from the bowel. Some people also require chemotherapy and radiotherapy to reduce the size of the tumour and prevent progression of the disease. During the operation the piece of bowel that contains the cancer is removed and the two open ends are joined together. The lymph nodes near the bowel may also be removed because this is the first place that the cancer could spread.
If surgery is not an option, then chemotherapy and radiotherapy are offered to stop the progression of the disease and to help control the symptoms.
Side effects after bowel surgery
After surgery the bowel will be highly sensitive and often the high-fibre foods that are usually recommended as part of a healthy diet actually give looser stools, which can be uncomfortable. Plenty of water or fluids should be consumed if diarrhoea occurs.
Some people are more wind-prone than before which can be uncomfortable. The chemist can prescribe peppermint water to drink or charcoal tablets that can help wind.
Hospital dieticians can be consulted if there are problems with food after surgery.
Colostomy (bag)
In some cases, the bowel cannot be rejoined straight away, and one end is brought out onto the skin of the abdominal wall. This is called a colostomy, and the opening of the bowel is known as a stoma. Bowel motions pass through the stoma into a colostomy bag, which is worn over the stoma. Many stomas are just temporary and can be reversed after a few months. If the cancer is very low in the rectum, or near the anus, the colostomy may be permanent.
Ileostomy
This operation makes an opening through the abdominal wall into the ileum, so that waste can be discharged out of the body without passing through the colon. It is only required rarely, if entire removal of the colon and the rectum is needed.
Chemotherapy
Chemotherapy is the use of drugs to treat cancer. Chemotherapy is a systemic therapy; it affects the whole body by going through the bloodstream. Chemotherapy gets rid of any cancer cells that may have spread from the bowel to another part of the body. It works by interfering with the rapidly dividing cells characteristic of cancer.
The body's normal cells grow and divide in a controlled manner. Cancer cells, however, grow and divide in total chaos—without any control or logical order. Chemotherapy works by stopping the growth or multiplication of cancer cells, thereby killing them.
Before surgery, chemotherapy may be used both to reduce the size of the tumour and to destroy cancer cells. After surgery, chemotherapy works throughout the body to kill cancer cells that may have spread.
When used immediately or following surgery, chemotherapy is very effective. If the cancer cells have broken away from the primary tumour, there will be relatively young and small clusters located somewhere in the body. These single cells or small clusters have plenty of nutrients and oxygen, and they are dividing quite rapidly. This is perfect timing for chemotherapy because chemotherapy works best on rapidly dividing cells. Cancer cells are more sensitive to chemotherapy than normal cells.
Depending on the drug (or drugs) given there may be anywhere from four to eight cycles of chemotherapy during an entire course of treatment. The commonest chemotherapy for colorectal cancer is 5-fluorouracil (5-FU) combined with leucovorin, this treatment course is known as 5-FU/LV (LV). The 5-FU is given through drips over a period of 48 hours.
Side effects
The side effects of chemotherapy happen because cancer cells aren't the only rapidly dividing cells in the body. The cells in the blood, mouth, intestinal tract, nose, nails, genitals, and hair are also undergoing constant, rapid division. The chemotherapy might affect them too.
Healthy cells that are affected by the chemo have an advantage over cancer cells because the body can repair the damage that chemotherapy does to normal cells. This explains why hair grows back, energy levels rise, and infections clear up. And while the body is fighting back, supportive medications can help control many of the side effects of chemotherapy.
While many side effects of chemotherapy fade quickly, others may take months or years to disappear completely.
Common side effects
The most common side effects of chemotherapy include nausea and vomiting, hair loss, fatigue and anaemia, infections, mouth sores, taste and smell changes, diarrhoea, menopause; fertility, and memory loss. Chemotherapy may affect the foods that can be eaten. Certain foods may aggravate a sore mouth, or bring on diarrhoea.
More serious side effects
Nerve function
The taxanes and platinum drugs can cause temporary nerve damage or permanent neuropathy (irreversible loss of nerve function).
Heart function
Some drugs can have a toxic effect on the heart.
Leukaemia
In very rare cases some drugs may cause a treatment-induced leukaemia (cancer of the blood cells).
Radiation Therapy/ Radiotherapy
Radiation is not commonly used to treat bowel cancer except when it affects the rectum or anal canal.
Radiotherapy is the use of x-rays and similar rays (such as photons) to destroy cancer cells. It can be given before or after surgery and reduces the risk of the cancer coming back. Radiation for bowel cancer is given externally. Sometimes radiotherapy and chemotherapy are given at the same time.
Side effects
Radiation therapy is relatively easy to tolerate.
