What is Bowel Cancer?
Bowel cancer is the cancer of large intestine (colon and rectum) and is also called as colorectal cancer.
Cancer in the large intestine is called as colon cancer and cancer in rectum (end part of the colon) is rectal cancer. Bowel cancer develops from uncontrolled multiplication of the cells that cover the inner lining of the bowel. Often, the cancers of bowel develop from polyps, the small and non-cancerous growths of tissues. Although bowel cancer affects people of all ages, it is common in people aged 60 years and above, and is one of the top three cancers seen in New Zealand.
Increased Risk Factors for Bowel Cancer
Certain factors are considered to increase the risk of developing bowel cancer include alcohol, smoking, high fat intake, family history of colorectal cancer, presence of polyps, and increased age (>60 years).
Bowel Cancer Symptoms
In the early stages, people with bowel cancer usually do not experience pain.
However the following symptoms may indicate colon cancer: Blood in stools (particularly if mixed with the motion), change in the bowel habits, such as thin stools, diarrhoea, and constipation; unexplained weight loss; fatigue; abdominal pain
Bowel Cancer Diagnosis
Bowel cancer is diagnosed by symptoms, medical history and other diagnostic procedures. These procedures include:
- Colonoscopy – It is a procedure done for inspecting the inside of the entire colon. It is performed using an instrument called colonoscope, a flexible tube with a tiny camera;
- Sigmoidoscopy – It is a test performed for the examination of the inside of the large bowel and the rectum;
- Barium enema – Rarely performed today, this is a procedure that involves insertion of barium containing fluid into the rectum and X-ray images are then captured to view inside the bowel If the bowel cancer is confirmed, staging is performed to detect the size, location, and stage of the cancer. Staging is performed using ultrasonography or a computed tomography (CT) of the abdomen, chest X-rays, magnetic resonance imaging (MRI) scans of the bowel and or liver.
- Faecal occult blood test- Faecal occult blood test (FOBT) is a test to determine small amounts of blood in the faeces. However this test does not diagnose colon cancer, it is a screening test, hence need to be performed during colonoscopy or sigmoidoscopy.
Bowel Cancer Treatment
Treatment of bowel cancer depends on the size, location, and stage of the cancer.
Severity of the bowel cancer may range from stage 1 (early stage; restricted to particular area) to stage 4 (advanced stage; spread to other parts of the body). Bowel cancer may be treated using chemotherapy, radiation therapy, and/or surgery.
Chemotherapy and radiotherapy
Bowel cancer can be treated using chemotherapy or radiation depending on the site and stage of the cancer. These treatments can be used as alone or in addition to surgery to destroy the remaining cancer cells and to prevent from further spreading. The decision regarding whether you require chemotherapy or radiation therapy will be discussed at a multi-disciplinary meeting (MDM) involving surgeons, radiologists and oncologists.
Surgery – Colon
The most common treatment for bowel cancer is surgery. More often a colectomy is performed, to remove the primary cancer. It is the surgical resection of all or part of the large intestine. The surgery is also called large bowel resection. Colectomy is performed under general anaesthesia by open surgery method or by laparoscopic method. The procedure takes about 1 to 4 hours. Open colectomy involves a single large incision of about 15cm made in the lower abdominal wall. The diseased part of the colon is removed and the healthy ends are sutured. If no healthy large intestine is left, an opening or a small incision called a stoma is created through the skin of the abdominal wall. The open end of the large intestine is stitched to the skin of the outer wall of the abdomen. Wastes will pass through the opening into a bag attached outside the body. This procedure is called colostomy. The operation can also be performed by a minimally invasive technique , laparoscopic colectomy, where several small incisions are made rather than one large incision. Three to five small incisions are made on the lower abdomen. A laparoscope, a telescopic video camera is used to see the inside of the abdomen, is inserted through an incision. Small surgical instruments are passed through other 2 incisions and colon is removed through another incision. Gas is filled in the lower abdomen and expanded for easy access. Diseased part of the colon is extracted. The healthy ends are reattached and all the incisions are closed with the sutures. The details around the surgical operation to the bowel will be discussed with you by the colorectal surgeon.
Surgery – Liver
Up to half of all patients with bowel cancer will present with secondaries (metastases) in the liver, either at the time that the primary bowel cancer is diagnosed (synchronous) or at a later stage (metachronous). Depending upon the location, number and size of the metastases within the liver they may be amenable to removal by surgery (hepatic resection) or ablation (see section on liver surgery). The most common method of removing part of the liver is by an open operation (laparotomy). In some instances it is possible to undertake the operation laparoscopically (keyhole surgery). The open technique is the preferred method for major resections particularly and in those tumors that are difficult to access. Laparoscopic liver resection involves the insertion of a camera, known as a Laparoscope, connected to a high intensity light is introduced through a small incision and a further three puncture wounds are made to allow the surgical instruments to be introduced. Once the liver has been resected a small incision is made low down in the abdomen to allow the tumour to be extracted. Irrespective of the method used the principals are the same: The liver is mobilized. The vessels to the portion being resected are isolated and controlled. A cut is then made through the liver substance (parenchyma) and care is taken to seal off the blood vessels and bile ducts that pass across the plane of transection.
Surgery – Lung
A minority (<10%) of patients with bowel cancer present with lung metastases that are amenable to surgical treatment. Treatment depends upon the number, size and site of the metastases. Typically they are resected by an open operation, however if they are small and peripheral they can be removed using keyhole surgery or through the diaphragm at the same time that abdomen is open.