More Western Australian people are being diagnosed with cancer than ever before. But there are a few good reasons for the increase in diagnoses. First, there are more people in WA - the population of WA is now almost 2 million. Also we are now living longer (on average) which means the population is getting older. Cancer is a disease of ageing, so the chance of being diagnosed with cancer increases as we get older. Finally, we are more actively looking for cancer, through early detection and screening programs.
Finding cancer early is important, because some cancers are easier to treat in their early stages.
- Screening is the testing of people with no obvious signs or symptoms of cancer. The main purpose of screening is to find cancer early and improve the chance of successful treatment.
- A screening test does not diagnose cancer. The test identifies people who are at higher risk of a specific cancer so they can be referred for further diagnostic investigation to determine if there is cancer present or not.
- Population screening is when a screening test is applied to the whole population or, more commonly, a defined subgroup of the population (eg women aged 50-69 yrs).
- Unfortunately, in reality there are no perfect tests, so screening is not foolproof. Sometimes disease is present and the screening test does not identify it (a false negative). Sometimes the disease is absent but the test identifies some abnormality (a false positive). Scientists work hard to reduce false negatives and false positives before screening tests are approved for use.
The World Health Organization (WHO) has a set of principles to assess whether cancer screening is worthwhile:
- It should be a common form of cancer with considerable illness (morbidity) or death (mortality)
- There needs to be an effective and accepted treatment
- Facilities for further diagnosis and treatment should be in place and available
- There must be an inexpensive, suitable test which is acceptable to the population
- The progression of the disease should be understood
- There must be an agreed policy on who to screen and treat
- Screening should be cost effective and the total costs should be consistent with health care spending in general
- Screening should be ongoing, not once-off
Unfortunately finding cancer early and fixing it may not always be the possible:
- Some diseases can be found but not fixed. You could be 'sick' for longer without any improvement in outcome.
- We could end up treating things that don’t need to be treated.
- False negatives can create a false sense of security.
- False positive may result in anxiety and sometimes illness.
- There may be a financial cost to individuals and screening takes time.
- There is a time and money cost to the health system.
- Some tests might be dangerous or uncomfortable.
Cancer screening can be a very good thing. But there’s a lot to it. Before a new cancer screening program is introduced there must be strong evidence that the proposed screening program reduces sickness and/or deaths from cancer.
Three national screening programs running in Western Australia:
Mammographic screening for breast cancer
BreastScreen WA has been running for more than 10 years. Women aged 50-69 years are invited for a mammography every second year. Target participation rate is 70%, with the current rate in WA closer to 60%.
Find out more about BreastScreen WA
In December 2017 the National Cervical Screening Program stopped using the Pap smear that looked for pre-cancerous changes to the cells, to the Cervical Screening Test that looks for human papillomavirus (HPV causes almost all cervical cancers) in the cells from the cervix.Women aged 25-74 will be invited every five years to take part in the program. Women who have had the HPV vaccine still need regular cervical screening.
Find out more about the WA Cervical Cancer Prevention Program
Faecal Occult Blood Testing (FOBT) for bowel cancer
Bowel cancer is a common cancer among men and women. Worldwide studies (Europe, UK and USA) show strong evidence that FOBT screening will reduce deaths from bowel cancer.The National Bowel Cancer Screening Program is currently inviting Australians aged 50, 54, 58, 60, 62, 64, 66, 68, 70, 72, 74 who hold a Medicare card or DVA gold card to take part in the program. In 2019, those aged 52 and 56 years will be invited. In 2020, when fully implemented, all Australians aged between 50 and 74 years will be offered free screening every two years.
- Read more about the National Bowel Cancer Screening Program.
For other major cancers the screening story is a little more complicated:
Prostate Specific Antigen (PSA) for prostate cancer.Prostate cancer is the most commonly diagnosed cancer in WA men. Early detection and treatment can significantly improve prostate cancer survival.
There are, however, no tests available with sufficient accuracy to screen populations of men for early signs of prostate cancer. There are high rates of uptake of PSA testing among WA men even though there is no strong evidence that this form of testing meets the WHO criteria (outlined earlier). There has however been an increase in 5 year survival from prostate cancer. Men aged 50 and over should talk to their GPs about prostate cancer testing.