Introduction
Each year in Europe, more than 297,000 people are diagnosed with colorectal cancer (163,00 men and 134,000 women). Overall, the number of new cases per year is considered to be stable or decreasing slightly. Approximately 30% of colorectal cancers are rectal cancers. Rectal cancer can be treated effectively, particularly if diagnosed at an early stage. It is important, therefore, that patients see their doctor if they develop any symptoms that could be due to bowel cancer - particularly those over the age of 40.
For more information on the symptoms and treatment of rectal cancer, see the relevant sections below.
Back to top
The Rectum
The rectum is the final part of the intestine before the anus. It is essentially a flexible tube about 18cm long and in its simplest sense, serves as a store for stools, expanding in volume as it fills.
The rectum is situated in the pelvis, surrounded by soft fatty tissue that allows the rectum to expand as it fills. This tissue is called the mesorectum and contains a number of lymph nodes.
Behind the rectum is the sacrum (the lowest part of the spine) and on each side, the rectum is surrounded by soft tissues and bone. In men, the bladder and prostate gland are situated in front of the rectum and in women, the bladder, vagina and uterus.
The rectum has little shelves in it called transverse folds, which help keep stools in place until it is emptied.
Only the very lowest part of the rectum has nerve cells that can detect pain. Pain, therefore, is rarely a symptom of rectal cancer. If a cancer starts or spreads to the junction with the anus or if the area around a cancer becomes inflamed there may be some pain.
Like the rest of the intestine, the rectum is lined with cells which secrete slime or mucus. Any inflammation of these cells causes an overproduction of mucus leading to frequent motions which are small and contain a lot of mucus and sometimes blood.
Back to top
Rectal Cancer
All cancers are uncontrolled growth of cells. In rectal cancer this uncontrolled growth happens in the cells lining the rectum and gives rise to a type of cancer known as an adenocarcinoma – the sort of cancer that develops from cells lining glands in the intestine. More than 98% of all cancers starting in the rectum are adenocarcinomas. The remainder are lymphomas and stromal tumours.
One of the characteristics of cancer is that it can spread to other parts of the body, either by directly invading neighbouring areas or because the cancer cells travel in the blood or lymphatic systems to other areas. Rectal cancer is a very predictable form of cancer. It starts as a polyp and gradually increases in size, spreading more deeply into the wall of the rectum. Once it is more than 3cm in size, it is likely to have grown through the rectal wall. Many tumours this size will also have spread to the nodes in the mesorectum. Rectal cancers can also spread to surrounding structures such as the bladder and other parts of the pelvis, and through the blood stream to the liver and bones.
Rectal cancer is not very fast growing. The cancer tends to double every 3 months. This means that by the time it is 5cm in size, it will have been developing for about 7 or 8 years.
Back to top
Rectal Cancer Risk Factors
Rectal cancer is rare below the age of 40 - although the number of new cases is increasing slightly in this age group. It becomes more common as one gets older with most cases being diagnosed in people over 60 years of age.
Diet is the most significant risk factor. Eating red and processed meat increases the risk of rectal cancer. Eating poultry has no effect on rectal cancer but fish has a protective effect, as does fibre and milk.
Obesity and alcohol are further risk factors. Overweight people are more prone to developing a range of cancers, leading to the idea that exercise and diet should be incorporated into health strategies to reduce the risk of many types of cancer.
The disease can be more common in particular families and people with a family history of colorectal cancer are obvious candidates for screening.
People who have previously been treated for cancer of the colon, rectum, ovary, uterus (endometrial cancer) or breast are also at increased risk of developing rectal cancer.
Individuals with some hereditary conditions, such as familial polyposis (where a number of polyps develop in the colon and rectum, which can become cancerous) and hereditary non-polyposis colon cancer or Lynch syndrome, have a greater risk of developing rectal cancer. These patients may be offered surgery as a preventative measure as well as regular check-ups to ensure that any cancer that does develop is detected as soon as possible.
Back to top
Preventing Rectal Cancer
There is no guaranteed way to prevent rectal cancer but there are things you can do to reduce the risk.
Rectal cancer is rare below the age of 40 - although the number of new cases is increasing slightly in this age group. It becomes more common as you get older with most cases being diagnosed in people over 60 years of age.
Diet is the most significant risk factor. Eating red and processed meat increases the risk of rectal cancer. Eating poultry has no effect on rectal cancer but fish has a protective effect, as does fibre and milk.
Obesity and alcohol are further risk factors. Overweight people are more prone to developing a range of cancers, leading to the idea that exercise and diet should be incorporated into health strategies to reduce the risk of many types of cancer.
The disease can be more common in particular families and people with a family history of colorectal cancer are obvious candidates for screening.
People who have previously been treated for cancer of the colon, rectum, ovary, uterus (endometrial cancer) or breast are also at increased risk of developing rectal cancer.
Individuals with some hereditary conditions, such as familial polyposis and hereditary non-polyposis colon cancer or Lynch syndrome, will normally be offered surgery (removal of most of the colon and rectum) as a preventative measure as well as regular check-ups to ensure that any cancer that does develop is detected as soon as possible.
Back to top
Symptoms of Rectal Cancer
Common symptoms of rectal cancer include:
- A change in bowel habit - having to go to the toilet more often, with looser motions particularly if they contain mucus and blood. Stools that are narrower than usual can be due to rectal cancer (as well as a number of other conditions).
- Blood - either bright red or very dark in colour and on the surface or mixed in with the stool, even if the bleeding does not continue.
- A feeling that the bowel does not empty completely
- A feeling of general discomfort in the abdomen sometimes with a feeling of being bloated or fullness.
And more rarely:
- Pain in the abdomen - especially in the lower left-hand side of the abdomen and cramp-like in nature
- Weight loss with no known reason
- Vomiting - particularly if associated with the other symptoms listed above
These symptoms may be due to a variety of conditions of which only one is cancer of the rectum. However, people over the age of 55 with these symptoms should seek medical advice promptly.
Back to top
Rectal Cancer Screening
In some European countries, a bowel cancer screening programme offers regular routine screening to all men and women in certain age groups (usually over the age of 55). Screening is helpful and each year identifies a number of people with rectal cancer who have no symptoms of the disease. However, what is more important than screening is awareness of the symptoms of rectal cancer (listed above) and seeking medical advice if they occur.
There are a number of ways of screening for rectal cancer, for example:
- Occult blood test - checking the stools for any sign of blood. This test identifies occult or hidden blood. If the test is positive, it does not mean that there is a cancer present, just that further tests are needed.
- A rectal examination - a lubricated gloved finger is gently inserted into the rectum to feel for anything abnormal. Like the occult blood test above, if this is positive it does not mean that there is a cancer present, just that further tests are needed.
- A sigmoidoscopy is an examination of the final 25cm of the intestines using a thin tube with a light attached. This allows a doctor to see the inside of the anus, rectum and the lowest part of the colon and look for anything abnormal and remove a sample for further examination in the laboratory.
- Colonoscopy is similar to sigmoidoscopy but uses a longer flexible tube. If the doctor sees polyps or anything abnormal it can be removed and submitted to further examination.
- During a colonoscopy or sigmoidoscopy, a biopsy can be taken to provide a small sample of tissue for examination under a microscope.
Back to top
Diagnosing Rectal Cancer
Although a physical examination of your abdomen may show no signs of rectal cancer, a tumour in the lower part of the rectum can often be felt during a rectal examination (a gloved finger is inserted into the rectum to feel if there is anything abnormal). However, this examination often produces a false negative result if the cancer is in its early stages or too high up in the rectum.
Various instruments can be used to look inside the rectum:
- the colonoscope is a long thin flexible telescope that can be pushed all the way round the colon to see inside the bowel and take samples for examination.
- a sigmoidoscope is shorter (about 25cm long) and can be used to examine the inside of the rectum and sigmoid colon and take samples for examination.
- a barium enema is an X-ray test which uses barium liquid to outline the inside of the colon and rectum which then shows up clearly on X-rays.
- biopsies – samples taken during a colonoscopy or sigmoidoscopy can be examined under a microscope in a laboratory to confirm the diagnosis.
Back to top
Staging Rectal Cancer
The treatment recommended for any patient with rectal cancer will depend on a number of factors unique to them, including their own preferences.
In rectal cancer one important factor in deciding on the most suitable treatment is the stage of growth that the tumour has reached.
To assess the extent of the cancer and how far it has spread, further tests are required. An MRI scan, ultrasound scan, CT scan or other tests are used to stage the cancer. The aim of staging is to find out:
- the size of the tumour in the rectum
- whether it has grown into or through the wall of the rectum
- whether it has spread to local lymph nodes in the mesorectum
- whether the cancer has spread to other areas of the body
The most common classification of the stages is the TNM system, which assesses the size of the Tumour, whether there is any spread to the lymph Nodes and whether there are any Metastases (whether it has spread to other areas of the body). The system is used to determine the best treatment options. It also helps assess the prognosis.
The Tumour (T) is assessed as follows:
- T1: the cancer is present in the lining of the rectum but has not invaded the rectal wall
- T2: the cancer is present in the muscular wall of the rectum
- T3: the cancer has spread through the muscular wall and into the surrounding tissues
- T4: the cancer has spread into other organs
Lymph Nodes (N) involvement is assessed as follows:
Metastasis (spread to other areas of the body) (M) is assessed as follows:
Back to top
Treatment of Rectal Cancer
There are a number of successful treatments available for rectal cancer including radiotherapy, surgery and chemotherapy. A combination of these treatments is frequently used with radiotherapy and/or chemotherapy frequently being used before surgery to reduce its size and to achieve better control of the cancer. The treatment strategy will depend on the staging of the cancer (see above).
Surgery
Surgery can be used in the treatment of all stages of rectal cancer and is usually performed in specialist hospitals. In most cases, radiotherapy or a combination of radiotherapy and chemotherapy is given before surgery as this improves the results of treatment significantly.
Early cancer can be completely removed using surgery. If the cancer is in a polyp, it can often be removed using a sigmoidoscope or colonoscope (see above). Other early stage cancers can often be removed using keyhole surgery.
Larger cancers are removed by cutting out most of the rectum containing the tumour and the mesorectum tissue around it. At the same time, lymph nodes near the rectum are usually removed and examined to check whether or not they contain cancer cells.
Most patients want to avoid a colostomy and surgeons are always aware of patients’ concerns about having a colostomy (an opening of the bowel onto the skin). However, sometimes there is no alternative. A colostomy may be temporary or permanent. Specialist health professionals can provide advice and help on how to deal with a colostomy.
Radiotherapy
Radiotherapy is usually given before or as an alternative to surgery. Frequently radiotherapy will be given at the same time as chemotherapy (sometimes referred to as chemoradiation or concurrent therapy) as acting together these two forms of treatment have a greater effect. In most centres, external beam radiotherapy is used.
External Beam Radiotherapy
External radiotherapy uses high energy X-ray beams generated from machines to kill cancer cells. Some normal cells will also be affected, but the treatment is planned so that the radiation is focused on the affected areas from multiple different angles. Normal tissues, therefore, receive a much smaller dose. In addition, normal cells are better at repairing themselves than cancer cells.
External radiotherapy is normally given as a series of short regular treatments in a radiotherapy department (each treatment may be referred to as a fraction) which are carefully calculated by the treatment team.
All radiotherapy treatments are designed to follow the shape of the cancer so that a higher dose of radiation can be more precisely targeted at the cancer avoiding neighbouring healthy tissue and resulting in fewer side effects.
External beam radiotherapy can be given as a 1 week course or over a 5 to 6 week period with up to 5 treatments a week. Giving a large number of small doses reduces the damage to healthy tissues.
Radiotherapy can also be given after an operation. This is usually because emergency surgery was required for some reason.
External beam radiotherapy is usually given if not all of the cancer could be removed during surgery. If the lymph nodes removed during surgery contain some cancer cells or as an alternative to surgery.
Chemotherapy
Chemotherapy is the use of drugs to treat disease and is also the term used for the use of drugs to kill cancer cells. In fact, these drugs kill normal as well as cancer cells but because the cancer cells are growing more quickly the effect on them is greater. Cancer cells cannot recover as well as normal cells following chemotherapy. Chemotherapy can be given as tablets or injections and is a systemic form of treatment which means that the drug travels through the body in the bloodstream, killing susceptible cancer cells throughout the body.
Monoclonal antibody treatment
Monoclonal antibodies are used in the treatment of many forms of cancer including colon cancer. However, as yet these treatments have not been helpful in rectal cancer.
Back to top
Looking after Yourself
Radiotherapy for rectal cancer, as the sole treatment or in combination with surgery is effective in many cases but can cause a number of side effects. Some patients will not experience any side effects, whilst others may find several troublesome. Fortunately many of these side effects disappear soon after the treatment ends and the symptoms can usually be treated, so if you do experience any problems it is important to mention them to your doctor or nurse, so they can give you the treatment you need.
Diarrhoea may occur during radiotherapy, and can be treated with medication if necessary. Many clinicians suggest that a low residue diet is helpful but not everyone agrees with this approach. Diarrhoea quickly clears up once treatment is finished.
Having to pass urine more frequently, sometimes with discomfort or a stinging pain is common. In most cases this will be helped by drinking plenty of fluids, but many doctors will check to make sure that there is no infection present – if there is an infection antibiotics will be prescribed.
Skin irritation over the lower part of the spine (sacrum), between the buttocks and between the legs, can be quite marked, but can be treated with hydrocortisone cream or ointment.
Whatever the problem, do not assume that nothing can be done about it – ask your doctor or nurse: do not just grin and bear it.
Back to top
Questions for your Doctor
Before making up your mind about the best treatment option for you, you will need information about your cancer, the treatments available in your own treatment centre and what they will involve, what to expect from the treatment, what side effects you might experience and how these may change over time as well as what your doctors believe would be most effective in combating your cancer.
For different patients the answers will be different, so it is important to discuss all these issues with your doctor so that you make the right choice for you.
You will have your own questions but some issues you might want to raise are:
1. What is the recommended treatment for me?
- What does the treatment involve?
- What are the benefits I might get?
- Are there alternative treatments?
- What may happen if I don’t have the treatment?
2. What are the chances of being cured?
- How good are my chances of getting those benefits?
- Could having the treatment make me feel worse? If so, in what way?
3. What are the risks and costs of treatment?
- What are the risks of the treatment?
- Are the risks minor or serious? How likely are they to happen?
- What care will I need after treatment?
- What happens if something goes wrong?
- Are there any financial costs to me?
Back to top
Conclusion
Over the past 15 years, the treatment of rectal cancer has improved considerably and with continuing research results will improve further still. One of the keys to securing better results for patients is catching the disease early on in its development. For these patients in particular, the results of current treatment are very good indeed.
Back to top