People aged will still be sent a free home test kit by the Australian Government every two years, but now people aged can also request a free screening kit to be mailed to them. Finding bowel cancer or precancerous conditions early is a key to reducing bowel cancer mortality and morbidity. Bowel cancer is one of only three cancers for which population-based screening is recommended; the others are breast cancer and cervical cancer.
For generic information about cancer screening, see the Principles of screening chapter. Adenomas are described as 'advanced' if they have certain features such as larger size 10 mm or more in diameter , contains villous growth pattern, or high-grade dysplasia. These features indicate a greater likelihood of progression to localised cancer and the risk of developing cancer elsewhere in the large bowel. Once cancer has developed, growth may occur gradually over 12 to 24 months or even longer.
Most people with advanced adenomas and many with early-stage bowel cancer experience no obvious symptoms. Bowel cancer survival is highly dependent on the pathological stage of tumour development at the time of diagnosis, as well as the treatments that follow. Earlier diagnosis is strongly associated with better prognosis. Patients with bowel cancer detected via participation in NBCSP were diagnosed at an earlier stage than patients with symptomatic cancers. Australian five-year survival rates for bowel cancer, based on South Australian and Western Australian data, are: [7][8].
There is evidence of an upward trend in survival figures over time in Australia, [6] due to a number of factors including improvements in surgical technique and more widespread use of adjuvant chemotherapy and radiotherapy. Cancers in the large bowel tend to produce low-grade bleeding, [10][11] so detecting blood in small often invisible concentrations in faeces is the basis for using FOBT to screen for bowel cancer. FOBT detects blood in faeces by identifying the chemical or immunochemical properties of haem and haemoglobin substances found in blood.
Acceptability of iFOBT as a screening tool is high. As early detection is the primary objective of screening, GPs are urged to recommend iFOBT as a screening tool for asymptomatic patients with no family history of bowel cancer. See role of GPs in screening for more information. The clinical recommendations assessed different age range scenarios and found that the age range was most cost-effective and had a balanced ratio of benefits to harms.
