Screening tests

We look at the major screening programs for bowel, breast and prostate cancer.
 
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01 .Introduction

Screening heartOver the course of a lifetime, you may be screened for a variety of diseases. We look at screening programs for bowel, breast and prostate cancer.

In 1968, heart attacks, strokes and other vascular diseases accounted for 56% of all deaths in Australia; by 2005, this had fallen to 35%.

Many GPs carry out informal or “opportunistic” screening for heart and circulatory disease risk. Regular blood pressure checks, blood tests to measure cholesterol and lipids (fats) and reviews of body mass index, together with reduced smoking rates, much improved treatment options for early stage disease and evidence-based advice, have resulted in marked decreases in potential years of life lost due to heart attacks, strokes and other diseases of the circulatory system.

This trend is encouraging, but there’s still room for further improvement in relation to prevention, early detection and treatment of these diseases.

Public health system criteria

  • The condition to be screened for should be an important health problem - it must be known that it can be present in an early form without any symptoms.
  • The test should be simple, safe, sensitive (few false negative results) and specific (few false positive results). The possible results of the test that are used to indicate the need for further testing or treatment should be clearly defined and widely agreed.
  • Early treatment of the condition tested for must be proved to be effective in bringing about better outcomes by reducing mortality and improving quality of life.
  • These better outcomes must clearly outweigh any potential harm to people from the screening, such as false positives leading to unnecessary psychological stress, invasive diagnostic tests and treatment with possible serious side effects.
  • The proposed screening program would not use resources that could save more lives and prevent more suffering if used in other ways.
  • The health system should ensure that positive screening test results can be promptly followed up – for example, colonoscopy following a positive bowel cancer test.

In your lifetime, you may well be screened for any one of these diseases – so it pays to understand the whys and wherefores.

 
 

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The National Bowel Cancer Screening program could save 2000 deaths annually when fully operational.

The program, which began in 2006, uses faecal occult blood tests (FOBT), but unfortunately one of the test kits was unreliable.

The program started again at the end of last year when about 600,000 test kits were rolled out. Men and women turning 50 between January 2008 and December 2010, and those turning 55 or 65 between July 2008 and December 2010, are now being offered a free FOBT kit for home use.

If you don’t want to wait for the program to catch up with you – especially if there’s a family history of the disease – you can use one of two home test kits from pharmacies:

  • Detectacol costs $29.95
  •  Insure costs $14.95. The Insure kit requires another $14.95 to be sent to the laboratory with the test card unless it is accompanied by a doctor’s letter.

You should consider FOBT if:

  • You are aged 50 or older, without symptoms and without a family history of bowel cancer. It is advised you take an FOBT every two years.
  • As with all screening tests, there will be false negative and false positive results. The FOBT is no exception, but it does meet international criteria for a screening test.
  • Remember that the benefits of screening, such as early detection, only apply if you are tested.

If your FOBT is positive, this does not necessarily mean cancer because several other conditions can result in bleeding in the bowel. However, it does mean you need further investigation, usually in the form of a colonoscopy, where the doctor can see the inside of the large bowel. Polyps that can go on to become cancerous, or early cancers, can be removed. But not all polyps or cancers bleed, so a negative FOBT does not guarantee no cancer. Another test that may be used, either alone or in conjunction with FOBT, is sigmoidoscopy, which examines the lower part of the large bowel. Deaths from bowel cancer in Australia were steady up to the mid-1980s. From then they have fallen by about 40%, probably due to a steady uptake of informal FOBT screening, reduced smoking, maybe better diets and more physical activity.

Contacts

Cancer Council Australia
Cancer Helpline 13 11 20 (cost of a local call)
Cancer Screening

The successful BreastScreen Australia program operates in more than 500 locations, using X-Ray mammography.

It’s aimed at women without symptoms aged 50 to 69, but women aged 40 and older can get free screening. It is one of the most comprehensive population-based screening programs in the world – well over 1.5 million women were screened in 2005/2006. Generally, mammography is less effective in younger women because of dense breast tissue being more opaque to X-rays. Older women (aged 70+) who have been involved in the program can elect to continue free two-yearly screening.

Despite actively recruiting women in the 50-69 year age group, only 57% of them are screened. This is disappointing, given the program’s objective is to screen 70% of this group. About 25% of screens are in women outside this age range. Breast compression during mammography may discourage some women, but early detection and a better chance of successful treatment can only happen if you are screened.

Effectiveness of screening

Regular two-yearly mammograms have been shown to pick up many small tumours in the early stages of development before they start to spread to other parts of the body. Most of these can be successfully treated.

A recent report says that between 1991-2006, BreastScreen Australia reduced breast cancer mortality in women aged between 50-60 by up to 29%. A rigorous accreditation process applies to all sites to ensure maintenance of the highest possible standards.

Research is ongoing to find ways to improve the false negatives and false positives of screening tests. Technologies other than X-Ray mammography, such as ultrasound and magnetic resonance imaging (MRI), are showing some promise, but so far only in conjunction with mammography.

Genetic screening can also be useful where there is a family history of breast cancer, but it can be expensive (see Genetic Testing Explained, left ) and raises quite difficult ethical issues, such as life insurance companies reducing their risk exposure and other family members not wanting to know their high-risk status. A useful reference is ‘Advice about familial aspects of breast cancer and epithelial ovarian cancer’, which can be found at www.nbocc.org.au (search for ‘familial aspects’).

Contacts

Cancer Council Australia
Cancer Helpline 13 11 20 (cost of a local call)
Cancer Screening

Prostate cancer can be present in an early and potentially treatable form without any symptoms, but if it’s detected from symptoms later on, the chance of a cure is low. In Australia’s Health 2008, the Australian Institute of Health and Welfare said:

  • The lifetime risk of prostate cancer for men is one in five (20%).
  • Prostate cancer is responsible for 29% of cancers in men (excluding non-melanoma skin cancers).
  • Prostate cancer is the second-most common cause of cancer deaths in males.

Possible prostate tests

Prostate cancer screening is controversial because many older men who screen ‘positive’ will undergo treatment with side effects such as incontinence and impotence. Elderly men are more likely to die of something else before prostate cancer claims their life. If you’re middle-aged rather than elderly, testing makes sense because the chance of dying from this often slow-growing cancer is much greater when it occurs at a younger age.

Prostate cancer often raises the levels of prostate specific antigen (PSA) in the blood, which is measured with a blood test. The acceptable level varies with age – 2.5 the maximum for the 40-49 age group, and 5.5 the maximum for the 70-79 age group. About 75% of positives are false alarms, and one study showed half of all men with an abnormal PSA returned to normal when tested six weeks later.

About 15% of men with prostate cancer will not have a high PSA. The false negatives and false positives contribute to the controversy around PSA testing. As well as a PSA test, your GP is also encouraged to perform a digital rectal examination (DRE) – checking the prostate by feel which will pick up about half of all tumours over 10mm. Medicare will cover one PSA test per year, and any subsequent tests to monitor suspected cancer. Guidelines for general practitioners suggest individuals need to make their own decision about prostate screening after being fully apprised of potential risks and benefits. The Urological Society is slightly more proactive, recommending that men aged between 50 and 70 with at least 10 years’ life expectancy should have PSA and DRE yearly after counselling.

For more information to help you decide if a prostate cancer screening test is right for you, go to www.andrologyaustralia.org/docs/PSAdecisioncard20041007.pdf

Contacts

Cancer Council Australia
Cancer Helpline 13 11 20 (cost of a local call)
Cancer Screening

“Bad” genes in our genetic makeup (our inherited DNA) may increase our chances of getting a certain disease. There are two ways to find out if you are at risk:

  • by looking at your family history for patterns of genetically determined (inherited) diseases
  • by having a genetic test for suspect genes linked to the specific disease.

However, we couldn’t afford to test everyone to see if they might get one of the top 30 diseases, and many diseases with a genetic component are the result of several genes interacting, so finding the “main” gene doesn’t always tell you a lot anyway. If genetic testing is suggested, it’s usually being done to confirm or refute a strong suspicion of inherited disease from your family history and/or ethnic background. If your family history shows an increased risk of breast cancer, genetic testing might be offered.

Women who carry BRCA1 and BRCA2 gene mutations are at high risk of developing breast and ovarian cancer and a personalised “screening” program may include mammography and /or ultrasound, and even checking for ovarian cancer. Screening may begin at a much earlier age than for “average risk” women – usually five years before the age at diagnosis of the nearest relative. 

Screening bodiesIssues raised by genetic testing

Genetic testing can raise tricky issues, so counselling is advisable before going ahead.

  • If the test is positive, and there is no treatment, such as with Huntington’s disease, will you feel worse?
  • Companies providing life or disability insurance may ask you for any genetic test results. If you do not know, you can answer questions honestly without losing policy benefits.
  • If a young person tests positive for significant mutations, this has significance for close relatives, especially parents.

Genetic testing costs 

For women with a high risk of breast cancer, genetic testing may be covered by the state health department. If the criteria for a free test are not met, the cost for a comprehensive check of BRCA1 and 2 can cost about $2000. This cost reduces for other family members who want to be tested to about $275.

Some exceptions to population genetic testing

For now, good arguments for whole-of-population genetic testing only apply in relation to pregnancy and newborns. Parents could be tested when planning a pregnancy for the cystic fibrosis gene, and if both have it, testing of the foetus can be done. Down syndrome testing is an example of testing during pregnancy for a genetically based abnormality. The newborn or Guthrie tests don’t actually involve DNA analysis; they look for protein markers in the blood that may indicate genetically inherited conditions.

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