There are 3 main methods:

• Surgery
• Radiotherapy
• Chemotherapy

What is the role of surgery?

Surgery is the main form of treatment for CRC. The aim is complete removal of the cancer with a length of normal bowel and its mesenteric lymph nodes. The 2 ends of the bowel are joined back (anastomosis). For a colon cancer, it is called a Hemicolectomy Operation, for a rectal cancer it is called an Anterior Resection.

For rectal cancers situated closed to the anus, complete clearance of the cancer involves removing the anus as well. The operation is called an AP Resection. The patient will have a colostomy in the right lower part of his abdomen in which the colon is attached to the skin and a new opening created for the discharge of faeces. The patient has to wear a colostomy bag to receive the faeces and learn how to take care of the opening and surrounding skin.

In some situations, a colostomy is temporary to divert the faeces while allowing anastomosis to heal. The colostomy is closed at a second operation.

In order to avoid a permanent colostomy, new surgical techniques have evolved to retain the anus.  The first method is to perform intestinal anastomosis as close to the anus as possible using mechanical staples rather than hand sewn stitches (sphincter saving surgery).  The second method is to create a ‘new anus’ using muscles from the thigh (neo-sphincter surgery)

Surgery in special situations:

1. Liver metastasis. In a fit patient with few isolated liver metastasis, removal of these metastasis can be performed at the same time as excision of the CRC. However this is not possible most of the time and patient with a CRC with liver metastasis is treated by chemotherapy.
   
   
2. Large inoperable CRC. In order to relief bowel obstruction, an intestine bypass surgery is required.
   
   
3. CRC causing intestinal obstruction or perforations.  In this acute situation, the patient is very ill and emergency surgery is required to relieve the obstruction or deal with the leakage of faeces.  When the patient has recovered, a 2nd or even 3rd operation maybe necessary to remove the tumour and join back the intestine (staged operation).

Laproscopic colon surgery (also known as keyhole surgery). CRC has been removed using such minimally invasive technique and the advantage is faster post-operative recovery with less pain. However it is technically difficult, time consuming and expensive. There maybe an increase in the risk of cancer implantation into the skin. At this stage this technique is under clinical evaluation.

Pre-operation preparation. As CRC surgery is a major operation, careful preoperative preparation is of utmost importance.

1. Individuals more than 70 years old or with chronic ill health (heart or lung problems, diabetes, hypertension, strokes, liver or kidney problems) are at high risk from surgery and general anaesthesia.  They are assessed carefully for fitness for surgery and general anaesthesia with clinical examination and investigations (chest x-ray, ECG, blood tests).
   
   
2. Preparations
   
   

   Patient	Pre-operation Preparation
   Smoker with poor lung function	Stop smoking, breathing exercises
   Ischaemic heart disease on antiplatelet therapy	Cardiac assessment, stop anti platelet drugs
   Ischaemic heart disease on antiplatelet therapy	Albumin transfusion
   Hypertension or diabetes mellitus	Careful control BP or blood sugar before operation

   
   
   
3. Bowel “preparation”.  All faeces have to be cleared out of the colon preoperatively to prevent contamination at the time of surgery.  Patient is admitted before the operation and given purgatives.  They are also allowed only liquid low fibre diet for a few days before operation.
   
   
4. Antibiotic cover.  As colorectal surgery involves coming into contact with faeces, a strong antibiotic is administered before the operation.

Immediate post-operation period. This crucial period which is about one week long is when the patient recovers from the operation.  He may develop a complication such as lung infection or leakage from the anastomosis and may die from it. He is on an intravenous drip which supplies him with fluids. After he recovers his intestinal function and is able to eat and drink, the intravenous drip is stopped. Medications needed during this period include antibiotics and a strong painkiller.

Radiotherapy

Radiotherapy is the administration of powerful radioactive rays to treat cancer. Its role in the treatment of CRC is secondary to surgical excision and is used in the following situations:

1. After surgical removal of a rectal cancer which has invaded the adjacent organs and/or nearby lymph nodes with the intention of mopping up residual cancer cells within the site of the cancer.
   
   
2. Preoperatively to a locally advanced rectal cancer to shrink it to a size where it can be surgically removed.

Radiotherapy is administered in daily sessions, 5 days per week over 4 to 6 weeks. Side effects are usually tolerable & temporary; abdominal cramps & pain, constipation or diarrhoea, cystitis, excoriation of perianal skin and generalized tiredness. 

Chemotherapy

Chemotherapy is the administration of toxic drugs to kill cancer cells which may be found at the site of the cancer or elsewhere in the body after surgery. It is indicated for patients with advanced CRC e.g. stage II, III or IV after surgery and it improves their chance of survival. The chemotherapy usually involves weekly injection of a cytotoxic drug called 5FU (5 Flurouracil) alone or in combination with other drugs for up to a year.

Because of its toxicity, chemotherapy also causes significant side effects.  The immediate side effects include nausea, vomiting, diarrhoea, susceptibility to infection, low white cell counts, hair loss. The long-term side effects include premature menopause, risk of a second cancer.