Excluding non-melanoma skin cancer,(1) colorectal cancer, commonly called bowel cancer, is the second most common cancer in both men and women in Australia. Eighty per cent of cases have no known hereditary genetic associations. Colorectal cancer is preceded by adenomas (polyps), which may become invasive cancer if undetected.
Incidence and mortality
There are more than 13,500 new cases each year. The risk of being diagnosed by age 85 is 1 in 10 for men and 1 in 14 for women.
In 2006, there were 3809 deaths from colorectal cancer.
Screening
Screening, using a non-invasive test for blood in the faeces, is available through the National Bowel Cancer Screening Program to Australians who turn 50, 55 or 65 years of age between January 2008 and December 2010. Abnormal tests are followed up with a colonoscopy.
Symptoms and diagnosis
Symptoms of colorectal cancer include:
- change in bowel habit with diarrhoea, constipation or the feeling of incomplete emptying
- thin bowel movements
- blood in the motion or abdominal bloating or cramping.
More general symptoms are:
- tiredness
- weight loss
- unexplained anaemia.
Diagnosis is by a colonoscopy.
Staging
Staging is determined by how far the cancer has penetrated through the bowel wall. Stage I is superficial, stage II is deeper and stage III is when the cancer has gone through the thickness of the wall or out into the tissues or lymph nodes beside the bowel. Stage 4 means the cancer has spread to other organs, commonly the liver.
A CT scan can be used to detect spread to the liver or lungs. A blood test to check if CEA (carcinoembryonic antigen) is elevated can be used to monitor the progress of the disease.
Causes
Risk factors include age, inherited genetic risk, inflammatory bowel disease, obesity and smoking.
Prevention
The risk of bowel cancer can be reduced by not smoking, a healthy diet with plenty of fresh fruit and vegetables, and maintaining a healthy body weight.
Treatment
Stage I and II disease can be treated with surgery alone to remove the bowel and surrounding lymph nodes. Stage III disease requires surgery and additional chemotherapy to try to prevent recurrence. Widespread disease is treated with chemotherapy. More recently targeted therapies are being trialled in addition to chemotherapy.
Prognosis
An individual’s prognosis depends on the type and stage of cancer, as well as their age and general health at the time of diagnosis. With stage I colorectal cancer, 90% of patients will still be alive at five years. This falls to 87% with stage II, 57% with stage III and 10% for widespread disease.??
For more information, contact Cancer Council Helpline on 13 11 20 (cost of a local call).
(1) Non-melanoma skin cancer is the most commonly diagnosed cancer according to general practice and hospitals data, however there is no reporting of cases to cancer registries.