Overview
Rectal cancer is the third most frequent cancer in both sexes in Europe. In 2006, 412,800 new cases of colorectal cancer were diagnosed across Europe, and in the same year there were 207,500 deaths from these cancers. Rectal cancer is estimated to account for 30% of all colorectal cancers. Data for rectal and colonic cancers are often combined but the two cancers are distinct, the treatment is different and mortality rates are not proportionate – for further information see section on prognosis.
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 with age, with most cases being diagnosed in people over 60 years of age.
Rectal cancer is not a very fast-growing tumour. Typically it doubles in size every 3 months. This means that by the time it is 5cm in size, it has been developing for about 7 or 8 years.
Rectal cancer can be treated very effectively, particularly if diagnosed at an early stage. However, often the diagnosis is not made until the cancer is well-developed, making treatment more difficult and the prognosis less favourable.
The reasons for late presentation of patients with rectal cancer are firstly that only the very lowest part of the rectum has nerve cells that can detect pain, and secondly that obstruction (a common presentation) occurs when the tumour is already extensive.
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Key Figures
| Total number of new cancer cases in Europe (2006) |
3.2 million |
| Total number of cancer deaths in Europe (2006) |
1.7million |
| Number of new colorectal cancer cases (2006) |
412,800 |
| |
(217,400 men) |
| |
(195,400 women) |
| |
307,000 (EEA) |
| |
(168,300 men) |
| |
(138,700 women) |
| |
297,200 (EU25) |
| |
(163,100 men) |
| |
(134,100 women) |
| Number of colorectal cancer deaths (2006) |
207,500 |
| |
(107,600 men) |
| |
(99,900 women) |
| |
142,700 (EEA) |
| |
(76,200 men) |
| |
(66,500 women) |
| |
139,400 (EU25) |
| |
(74,500 men) |
| |
(64,900 women) |
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Cancer Types
More than 90% of all cancers starting in the rectum are adenocarcinomas. The remainder are lymphomas and GastroIntestinal Stromal Tumours (GIST). Tumours of the anal canal are usually squamous cell tumours.
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Causes of Rectal Cancer
Age: Rectal cancer is rare below the age of 40. Most cases affect people over 60 years of age.
Diet is the most significant risk factor. Eating red and processed meat increases the risk of developing rectal cancer. By contrast, fish, fibre and milk have a protective effect.
Obesity and alcohol are also risk factors.
The disease can be more common in particular families and those with a family history (1st and 2nd degree relatives) of
colorectal cancer should undergo screening.
Having had previous treatment for cancer of the colon, rectum, ovary, uterus (endometrial cancer) or breast is also a risk factor for developing rectal cancer.
Hereditary conditions: people who have
Familial Polyposis and
Hereditary Non-Polyposis Colon Cancer or
Lynch Syndrome have a greater risk of developing rectal cancer.
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Screening for Rectal Cancer
People at high risk should attend regular screening (every 5 years) to ensure that any cancer that does develop is detected and treated early.
Screening is available in some European countries - usually to people in higher risk age groups (i.e. over the age of 55) or with a family history.
Screening procedures for rectal cancer include:
- Checking stools (or faeces) for any sign of blood (shown to be effective in reducing the mortality rate in a screened population)
- Colonoscopy (see below for more details)
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Prevention of Rectal Cancer
A healthy, low-fat diet which is low in red and processed meat and high in protective foods, such as milk and fibre, lowers the risk of developing rectal cancer. Moderate alcohol intake combined with a healthy diet and regular exercise will reduce the statistical risk of developing rectal cancer.
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Common Symptoms
Common symptoms include:
- A change in bowel habit - more frequent, looser motions, particularly with mucus and blood.
- Stools that are narrower than usual can be due to rectal cancer.
- Rectal bleeding - either bright red or very dark in colour, on the surface or mixed in with the stool, even if the bleeding has stopped.
- A feeling that the bowel does not empty completely (tenesmus).
- 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, which is cramp-like in nature.
- Weight loss with no known reason.
- Vomiting, particularly if associated with the other symptoms listed above.
All these symptoms may be due to other conditions, but in the over-40s, they require further investigation even if they disappear for a time.
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Diagnostic Tests
Standard physical examination may show no signs of rectal cancer.
A tumour in the lower part of the rectum can often be felt during a rectal examination, but to detect cancers higher up in the rectum, either a colonoscopy or a
sigmoidoscopy is necessary.
Biopsies can be taken for histology using either technique.
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Staging Rectal Cancer
The recommended treatment depends on a number of factors including the stage of growth that the tumour has reached.
Staging determines:
- 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 of disease is the
TNM system, which assesses the size of the
Tumour, whether there has been any spread to the regional
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.
For the tumour (
T), the classification is 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
Involvement of the
lymph nodes (
N) is assessed as follows:
Metastasis (spread to other areas of the body) (
M) is assessed as follows:
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Treatment
The available treatments for rectal cancer are:
- Surgery
- Radiotherapy
- Chemotherapy
- Chemoradiation (combined radiotherapy and chemotherapy)
Patients may receive some of all of these treatments.
Surgery
Surgery can be used in all stages of rectal cancer. Preoperative radiotherapy is standard treatment in almost all cases.
Surgery is best undertaken in specialist centres treating high volumes of patients, as the results in these centres are better for patients.
Early cancer can be completely removed
only using surgery.
Polyps can often be removed using a sigmoidoscope or colonoscope.
Larger cancers are removed by cutting out a section of rectum containing the tumour and
mesorectum tissue (with
lymph nodes) around it.
Surgical treatment for rectal cancer has changed dramatically over the past 10-15 years. The standard surgical approach is a total mesorectal excision (TME), which often allows removal of the cancer with preservation of sphincter function, thus usually avoiding the need for a colostomy.
If an anastomosis is not possible at the time of surgery, a colostomy will be required. Stomas may be temporary or permanent.
The pathologist will be able to confirm whether the
mesorectum has been removed entirely.
Combined preoperative chemotherapy and radiotherapy with delayed surgery reduces tumour size.
Complications of Surgery and their Management
Complications of surgery can include bleeding from the operative site, infection, perforation of the bowel leading to peritonitis and a breakdown in the anastomosis if one is performed. The management of all these problems generally entails more surgery with supportive therapy including antibiotics, intravenous fluids and blood transfusions as appropriate.
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Radiotherapy
Radiotherapy is usually given before surgery but may also be given
after surgery. There is strong evidence for the use of preoperative radiotherapy to provide better results and also that preoperative radiotherapy causes less toxicity than post operative treatment.
External beam 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.
Small tumours (stage I) which are contained within the rectal wall can be treated by surgery alone.
Stage II and stage III tumours are treated with preoperative radiotherapy or chemoradiotherapy - both have been shown to have the same beneficial effect.
Tumours with a greater degree of spread are also best treated with
chemoradiation before surgery.
Chemoradiation can also be used after surgery if:
- during surgery the cancer is found to be more advanced than predicted before surgery (for example, if a stage III cancer was thought to be a stage II cancer before surgery)
- emergency surgery is required for some reason
Exactly how the radiotherapy is given varies from hospital to hospital. In some, a short one week course is used but in others a 5-6 week course is preferred.
External beam radiotherapy is usually given over a 5-6 week period with up to 5 treatments a week with as many as 25 to 28 treatments in total. Giving a large number of small doses reduces the damage to healthy tissues.
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 is usually given postoperatively if not all the cancer could be removed during surgery, if the
lymph nodes removed during surgery contain some cancer cells or as an alternative to surgery.
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Side Effects of Radiotherapy and their Management
Acute side effects such as increased bowel frequency with diarrhoea (more common with
chemoradiation), acute proctitis (causing a mucus discharge) and dysuria (pain on passing urine) often occur during treatment.
The symptoms appear to be linked more to the size of individual doses of radiotherapy rather than the total dose. They generally improve quickly after treatment has finished.
Management of diarrhoea involves the use of antispasmodic and/or anticholinergic medications.
Concurrent chemotherapy, especially using
5-FU which has significant gastrointestinal toxicity, exacerbates the acute gastrointestinal effects. Proctitis can be treated with a range of anti-imflammatory medication.
Delayed complications are less frequent but tend to affect patients treated with surgery and radiotherapy. These are due to vascular insufficiency and fibrosis in affected organs including the bladder, urethra and small intestine. Changes in sexual function and adhesion formation may also occur. Symptoms commonly occur 6-18 months following completion of treatment.
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Chemotherapy
Chemotherapy drugs travel through the body in the bloodstream killing cancer cells thoughout the body.
Side Effects of Chemotherapy and their Management
Cytotoxic drugs cause some damage to normal cells as well as cancer cells. The most vulnerable cells are in the lining of the bowel, the gonads and the bone marrow.
Consequently, the most common side effects are vomiting, tiredness and myelosuppression. Generally, these side effects are short-term and will gradually recede once the treatment has finished. However, the side effects do vary from person to person.
5-FU is a drug commonly given to patients with rectal cancer and in 30% or more of patients it can cause:
- Diarrhoea
- Nausea and possible occasional vomiting
- Mouth sores
- Poor appetite
- Watery eyes and a sensitivity to light (photophobia)
- Taste changes - a metallic taste in the mouth
- Low blood counts
- Increased risk of infection, anaemia and/or bleeding
Most of these symptoms subside quickly after treatment (within 3 weeks) and can be treated symptomatically if they occur. Infection requires active management with antibiotics.
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Chemoradiation
Chemotherapy and radiotherapy can be used as a combined treatment in some cases, known as
chemoradiation, and are usually carried out preoperatively.
Side effects are the same as with radiotherapy and chemotherapy, but diarrhoea is more frequent in these patients.
Monoclonal Antibody Treatment
Monoclonal antibodies are used in the treatment of many forms of cancer. They target specific proteins necessary for the progression of the cancer, causing very few side effects. In
colon cancer, treatment with these agents has been shown to be effective, but as yet they are not of proven benefit in rectal cancer. This is an area of continuing research.
Side Effects of Monoclonal Antibody Treatment
Monoclonal antibodies have very few side effects. They do not cause hair loss, or any of the other side effects associated with chemotherapy.
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Prognosis
Many factors affect prognosis. These include the
stage of rectal cancer, the patient's age, general health and their individual response to treatment (which will vary). For this reason, statistics can only be considered as a general guide as they are produced by grouping together patients in whom these factors are similar but not identical. These figures are historical, often covering a 10 or 20 year period, and so do not reflect improvements in survival through more modern treatment.
Survival rates indicate the percentage of people who survive the disease for a specific period of time after their diagnosis - usually 5 or 10 years.
Published 5-year survival rates for rectal cancer are:
- 90% for localised cancers (T1 and T2)
- More than 65% for cancers that have spread outside the rectum, but not formed distant metastases (T3)
- Approximately 10% for cancers that have spread outside the rectum and have formed distant metastases (T4)
- About 35% for cancers not staged at the commencement of treatment
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Key Trends
In most countries, the number of new cases diagnosed each year is stable or falling slightly.
Potential Developments
Genomics may help in determining which patients are best suited to particular treatments, so avoiding giving the toxic side effects of treatment to patients where the treatment is unlikely to succeed overall.
The role of monoclonal antibodies in the treatment of rectal cancer is an area of research, but as yet these agents are of no proven benefit in rectal cancer.
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