By Dr Ananya Mandal, MD
Who treats colorectal cancer?
Those detected with colorectal cancer need to be treated and cared for by a multidisciplinary team. The team comprises of:
Oncologist or cancer specialist
Specialist cancer surgeon
A radiotherapy and chemotherapy specialist
A specialist nurse
A social worker
Factors that influence the success of treatment
Treatment and its success depends on several factors. Some of these include:
Type of cancer
Size of the tumor
General health and age of the patient to determine the capability to withstand the operation
Stage of the cancer
Grade and aggressiveness of the cancer
Types of treatment
Treatment of colorectal cancers comprises of surgery, chemotherapy and radiotherapy. Newer biological therapies are also being used. Treatment plan involves the patient’s personal choices as well as the above stated factors.
If the cancer is in the rectum, radiotherapy will usually be used to shrink the tumour, then surgery may be used to remove the tumour. Sometimes, radiotherapy is combined with chemotherapy, which is known as chemoradiation.
For stage 1 colorectal cancer surgery is the first choice and may be followed up with other modalities of therapy. For stage 2 or 3 of colorectal cancer surgery may be used to remove the cancer and, in some cases, nearby lymph nodes. This is followed up by a course of chemotherapy to stop the cancer from returning.
Stage 4 cancer is usually advanced and symptoms can be controlled and the spread of the cancer can be slowed using a combination of surgery, chemotherapy, radiotherapy and biological therapy.
Surgery for colorectal cancers
Surgery is usually the main treatment for colorectal cancer. This cannot be the first line of treatment in around 20% of cases where the cancer is too advanced to be removed by surgery. Patients after cancer surgery may need additional chemotherapy, radiotherapy or biological therapy.
If the cancer is in stage 1 and the tumor is small, just a small piece of the lining of the colon wall is removed. This is called local excision. If the cancer has spread to muscles surrounding the colon, entire section of the colon needs to be removed.
Removing some of the colon is known as a colectomy. If the left half or right of the colon is removed it is called left-hemi colectomy or right hemi- colectomy respectively. If the middle section of the colon is removed, it is called transverse colectomy and if the lower section of the colon is removed, it is called sigmoid colectomy.
Colectomy may be performed in an open surgery where the abdomen is cut open or may be performed using tiny incisions and a laparoscopic instrument called laparoscopy. A laparoscopic colectomy is a type of ‘keyhole surgery’. Here the surgeon makes a number of small incisions and inserts tube like instruments guided by a camera to remove a section of colon. Laparoscopic surgeries have an advantage of faster recovery time, less bleeding and less post-operative pain.
Radiotherapy for colorectal cancers
Radiotherapy can be given before surgery, especially in cases of rectal cancer, or may be used to control symptoms and slow the spread of cancer in stage 4 or advanced cancer. In the latter case it is known as palliative radiotherapy.
Radiotherapy may be given as external radiotherapy, where a machine is used to beam high-energy waves at the tumor or may be given as internal radiotherapy or brachytherapy where a radioactive tube is inserted into the rectum and placed next to the tumor to kill the cancer cells.
External radiotherapy is usually given daily, five days a week for around five weeks. Each session of radiotherapy is short and will only last for 10-15 minutes. Internal radiotherapy can usually be performed in one session before surgery. Palliative radiotherapy is usually given in short, daily sessions, with a course ranging from 2-3 days to 10 days.
Chemotherapy for colorectal cancers
Chemotherapy may be given before surgery for rectal cancer in combination with radiotherapy, or given after surgery to prevent the recurrence of the cancer or may be given to slow the spread of stage 4 advanced cancer. The latter is known as palliative chemotherapy.
There are several anticancer medications used as chemotherapy for colorectal cancers. These may be oral (taken as pills) or may be given as injections and infusions. Patients may need regular daily sessions of chemotherapy over the course of one or two weeks before having a break from treatment for another week.
Some of the drugs include 5-fluorouracil (5-FU) or Capecitabine, Leucovorin (LV, Folinic Acid) and Irinotecan, Oxaliplatin.
Chemotherapy with drugs is accompanied by several side effects including nausea, vomiting, hair loss, diarrhea, anemia, risk of infections and bleeding tendencies. These side effects should gradually pass once the session passed.
Drugs like cetuximab, bevacizumab and panitumumab, are a newer type of medication known as monoclonal antibodies. This target the special proteins found on the surface of cancer cells, known as epidermal growth factor receptors (EGFR). As EGFRs help the cancer to grow by targeting these proteins, biological treatments can help prevent the cancer spreading. Biological treatments are usually used in combination with chemotherapy and radiotherapy.
Reviewed by April Cashin-Garbutt, BA Hons (Cantab)