Colon and Rectal Cancers
Colorectal cancers account for the 3rd most common cause of deaths attributed to cancer.
Most are glandular tumours (adenocarcinomas) that can present insidiously because of their location. The most common symptoms, if present or noticed, are disturbance of bowel habit and rectal bleeding - either as dark stools (malaena) or bright red blood. However, colorectal cancers are often clinically silent until symptoms of fatigue, weight loss and anaemia occur due to occult bleeding. Please present to your local doctor if you are concerned by any of these.
Surgery is the mainstay of treatment of cancers of the colon and rectum. However, colon cancers are treated very differently to rectal cancers.
Colorectal cancers are such a concern that a National Bowel Cancer Screening project has been implemented, which invites Australians turning 50, 55, or 65 years of age, who hold a Medicare card or DVA gold card, to take part in the program. Doing a Faecal Occult Blood Test (FOBT), which involves examination of a faecal specimen for traces of blood every two years, can reduce your risk of dying from bowel cancer by up to one third.
The National Health and Medical Research Council recommends that organised FOBT screening of average risk people should commence at 50 years of age. A family history of bowel cancer is considered a significant risk factor and should be discussed with your local doctor as screening is often recommended to commence earlier depending upon all the risk factors.
A diagnosis of colorectal cancer is confirmed by a specialist surgeon or gastroenterologist, who will perform a colonoscopy, which is a small telescoped camera introduced into the bowel under sedation. A biopsy of the tumour is required to make the official diagnosis.
For tumours of the large bowel (colon), chemotherapy is often recommended after surgery in order to reduce the risk of spread of microscopic disease and improve overall survival. This is especially the case when the tumour has advanced through the entire bowel wall, spread to lymph nodes removed with the bowel, has invaded a nearby organ or if the patient presents with obstruction or perforation of the bowel.
The patient's age, prognosis, performance status and, mostly, their preference are all taken into account when recommending further treatment.
Radiotherapy after surgery, for colon cancers, is only offered in instances where the tumour cannot be entirely removed and curative treatment is still desired. It is often given in combination with chemotherapy in these cases.
For tumours of the rectum, six weeks of pre-operative chemotherapy and radiotherapy are usually recommended together in order to reduce the risk of recurrence and shrink the tumour, which sometimes permits an easier operation.
Surgery is then performed six weeks after completing combined chemo-radiation, which gives the body time to recover. Sometimes, further chemotherapy or other systemic therapy is recommended also, depending upon what the specialist pathologist sees in the tumour under the microscope after surgery.
Quite often, the pathologist can see no tumour once the rectum has been removed, indicating a complete response to chemoradiation, but the surgery is still essential, when it can be performed.
The side effects of radiotherapy for colon and rectal cancers are unique to each case, as it depends upon the extent of surgery and whether it is delivered before or after surgery.
Combined chemotherapy and radiotherapy before surgery is more common for rectal cancers and is usually very well tolerated over the five week course.
Common, early side effects from the radiotherapy component include tiredness, a skin reaction and increased use of the bladder and bowel associated with some mild discomfort. When surgery is performed, most of the tissue which has been treated is then removed, which makes late side effects from radiotherapy rare.