Screening and Early Detection
Screening is the examination of asymptomatic or well people in order to classify them as likely or unlikely to have a disease. It is a process aimed at reducing the risk of developing cancer or its complications through early detection and treatment.
Well-established principles apply to screening. The main underlying principle is to do the least harm to achieve the greatest measurable benefit for the population. There may be adverse effects of screening for some people (such as anxiety if they are told that they are at high risk of developing a disease, or if there are ‘false positives’ indicating a person has a disease when in fact they do not.). Because such people would not have experienced the adverse effects had they not been invited to take part in screening, it is very important that there is good evidence of benefit from screening, and that screening tests and follow-up investigations carry low risk.
In principle, it is important to educate people to recognise the early signs and symptoms of cancer in order to encourage early presentation, and thus early treatment. However, although some cancers (such as melanoma) have early warning signs that are easily identified, many do not. Furthermore, detection of a cancer before it appears to have spread does not always lead to an improved outcome. Therefore, early detection should be focused on those cancers where this has been shown to reduce mortality and morbidity.
The following cancer screening programmes operate in New Zealand:
New Zealand’s free national breast screening programme checks women for signs of early breast cancer. Regular mammograms are available for women aged between 45 and 69 to reduce their risk of dying from breast cancer.
National Cervical Screening Programme
The National Cervical Screening Programme is available to all women in New Zealand between 20 and 70 years old. The screening test checks for abnormal cell changes to the cervix which are a precursor to cancer. If abnormalities are detected treatment can be offered to prevent cervical cancer from developing.
Bowel Screening Pilot
In 2010 the New Zealand Government announced that it was funding a Bowel Cancer Screening Pilot Programme, which will be run in the Waitemata DHB.
The four year pilot will begin by late 2011 to determine whether a bowel screening programme should be rolled out nationally. No decision will be made on implementing a national programme until all monitoring and evaluation data from the pilot has been analysed.