What are the colon and rectum?
The colon and rectum together make up the large intestine or large bowel.
The colon is the first part of the large intestine and the rectum is the last part. The colon lies within the abdomen or tummy, and is about 150 centimetres (or 5 feet) in length typically. The rectum is approximately 15 cm (0.5 feet) and lies deep and within the pelvis.
The main purpose of the large intestine is to absorb water and some salts. In addition, the rectum also has a temporary reservoir role for stool, before defecation through the anal canal.
What is bowel cancer / colorectal cancer?
Cancer in general is any type of disease that occurs when the cells that make up our body start to grow out of control and develop the ability to invade into and beyond where they normally belong.
In Bowel cancer, also called colorectal cancer, the cancer affects the colon or rectum. Bowel cancer is a common cancer in the UK.
In Bowel cancer, the normal cells of the bowel become abnormal and grow out of control to form lumps. Often in the initial stages, the lump is not cancerous and is referred to as a benign tumour or benign lump or a benign polyp, and although the cells can grow and form a lump, they are unable to spread or invade through the bowel or into nearby structures. If discovered at this stage, your doctors can often remove this lump without a major operation.
When the cells become cancerous however, they can grow through other layers of the bowel; or invade into nearby structures; or even spread to other parts of the body like lymph glands, the liver, and the lungs.
In general, bowel cancer is a treatable cancer, however the earlier it is diagnosed the easier it is to treat and cure.
It is generally believed that most bowel cancers take many years to develop (for example between 5 and 10 years).
What are the symptoms of bowel cancer?
The symptoms of bowel cancer are not always easy to spot and in some patients there may be no symptoms at all for quite some time.
For those who experience symptoms, these can include the following:
- A pain or lump in the tummy
- A persistent change in bowel habit
- Bleeding from the back passage or blood in the poo
- Unexplained and persistent weight loss or tiredness
At times the cancer can fill the bowel tube and block it. This can lead to severe pain, bloating, sickness, and or constipation. This is called bowel obstruction and is a medical emergency.
How is bowel cancer classified?
Bowel cancer treatment is dependent on its classification. As a result classifying bowel cancer accurately is very important as part of its treatment.
Classification of bowel cancer is also called “staging” bowel cancer. In simple terms it’s a method of describing where the cancer is, what structures may be involved, and how far it has spread.
Accurate staging may involve a variety of tests including endoscopy, and scans such as CT scans, MRI scans, or PET scans. Sometimes your surgeon or doctor may also want to assess the lining of the tummy by an operation in case cancer cells are in this area but not visible on scans. However sometimes it might not be possible to know precisely what the stage of a cancer is until after surgery.
Once the stage is known as accurately as possible, doctors can best determine the treatment options to offer.
There are several ways of staging bowel cancer. These include a so called TNM staging system, and a number staging system. Below we have provided a simplified description of the systems most commonly in use.
The most common way of staging bowel cancer is with the TNM staging system. In this method, “T” refers to the main tumour itself and how far through the bowel wall the cancer has spread; “N” refers to whether the cancer has spread to nodes nearby; and “M” refers to whether the cancer has spread to other parts of the body, most commonly the liver or lungs.
The T stage is divided into 4 subgroups described below:
- T1: Cancer in the inner layer of the bowel only
- T2: Cancer in the muscle layer of the bowel wall
- T3: Cancer involves the outer layer of the bowel wall
- T4: Cancer has gone through the bowel wall (and may have invaded adjacent nearby structures)
The N stage is divided into 3 subgroups, N0, N1, and N2.
- N0: None of the lymph nodes around the bowel contain cancer
- N1: Between 1-3 nodes contain cancer cells
- N2: 4 or more nodes contain cancer cells
The M stage is divided into 2 subgroups.
- M0: Cancer is not believed to have spread to other organs in the body
- M1: Cancer has spread to other organs
The TNM staging system is the most commonly used method. However you may also hear about the number staging system. In this method, there are 4 stages described.
- Stage 1: The cancer involves the lining or muscle layer of the bowel only
- Stage 2: The cancer involves the bowel only but has not spread to any lymph nodes or other organs
- Stage 3: The cancer has spread to involve lymph nodes around the bowel but has not spread to other organs
- Stage 4: The cancer has spread to other organs in the body
What causes bowel cancer?
The precise cause of bowel cancer in any one person is difficult to identify.
However there are a number of risk factors for bowel cancer that can increase the chances of it developing in a person’s lifetime. Having one or more of these risks factors does not imply that a person will definitely have bowel cancer; it just means that the chances of them developing bowel cancer will be higher than if they did not have the risk factor.
1. Age: The risk of bowel cancer increases with age
2. Not enough exercise or activity
3. Diet: Too much processed or red meat; and too little fibre or fruit and vegetables
4. Being overweight
7. Non-cancerous growths or polyps of the bowel
8. Inherited genes or a family history of bowel cancer in close relatives
9. Other bowel conditions such as Crohns disease or Ulcerative colitis
10. Previous radiotherapy
Some risks are modifiable (e.g smoking) however some may not be (e.g inherited genes). If you are concerned about whether you have one or more of these risks, you can talk to your doctor and they may be able to suggest ways to reduce your risk.
How is bowel cancer treated?
There are lots of treatment options available for bowel cancer. In general, bowel cancer is a treatable cancer, however the earlier it is diagnosed the easier it is to treat and cure.
The treatment offered depends on several factors including the stage of the cancer, where the cancer is, other medical conditions and previous treatments, and the general state of health of individuals.
The best options for treatment are determined by a panel of medical staff in what is termed a multi-disciplinary team (MDT meeting). This team is composed of cancer specialists (oncologists); radiologists; pathologists; nurse specialists; and surgeons.
Sometimes the aims of treatment are to eliminate all cancer for good and to cure.
Other times, especially if the cancer is very advanced or if individuals are medically unfit for some of the treatment options, the aims of treatment are not to cure as such, but to help reduce symptoms from the cancer, help people live longer with their cancer, and improve their quality of life. This is known as palliative treatment.
Occasionally the precise aims of treatment (either curative or palliative) are not clear cut however.
Surgery is the key treatment for those with early stages of cancer and for some with advanced disease. Where the cancer is advanced or spread, then combinations of treatment may be offered, including combinations of chemotherapy or radiotherapy or surgery.
Surgery for bowel cancer
Surgery remains the commonest type of treatment for bowel cancer.
However, sometimes it may not be suitable, or it may need to be combined with other treatment options such as chemotherapy and or radiotherapy. These may be sequenced before or after surgery depending on the location and stage of bowel cancer.
There are many different surgical options for bowel cancer and your medical team will advise you about the best options for you. In general, the type of surgery offered will depend on the location and the stage of bowel cancer, as well as a few other factors.
Broadly, the following types of surgery may be offered:
- Local excision: For some small or very early cancers, your doctors may recommend a local excision only using miniaturised cameras that can remove the main lump alone, but not much of the bowel itself.
- Keyhole or Laparoscopic surgery: This is a minimally invasive method of surgery where a complete section of large bowel will be removed. In this type of surgery your surgeon will make several small keyhole cuts in the tummy and insert a camera (laparoscope) through one of the openings to see inside your tummy. Long surgical instruments are passed inside the tummy to then remove the cancer. This is generally the preferred type of approach if possible as typically recovery will be swifter. Occasionally your surgeon may need to change from a keyhole approach to an Open approach at surgery if felt to be safer.
- Open surgery: This is a conventional approach to removing bowel cancer and like keyhole surgery, involves removing a complete section of large bowel. In this situation however, the same operation is conducted through a larger cut in the abdomen. It is used if there has been previous extensive surgery to the abdomen, or if the cancer is very advanced, as keyhole surgery may not be suitable in these situations.
- Exenterative surgery: This is a specialist and very major operation reserved for certain very advanced cancers, or those that come back in the same area. It is not a common operation. Exenteration refers to a form of radical and extreme removal of the tissues and organs in a body cavity, and it may be conducted for cancers affecting the tummy or the pelvis, and it often involves the removal of several organs or body parts (and not just the affected segment of bowel). The procedure is followed by reconstruction of the relevant organ systems. This type of surgery is only offered if it is the only opportunity to eliminate or control a very complex cancer. There are several different types of exenterative surgery and the type needed will be advised by your surgeon based on the location of your cancer and the organs believed to be involved.
The information on these web pages is provided in very broad and simple terms mainly and is not a comprehensive compendium. The medical team involved in your or your friend or family members care will be able to fill in any extra information you require.
More information may also be found on the Cancer Research UK; Macmillan Cancer Support, and the Association of Coloproctology of Great Britain and Ireland Websites.