Early detection

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.

Find out how to find cancer early in women and men.

Basic terminology

• 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.

Some examples of successful screening programs running in Western Australia include:

• 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

• Pap smear screening for cervical cancer

  Pap smears detect pre-cancerous cells and allow for early, successful intervention. There has been a considerable drop in the cases of and deaths from cervical cancer due to this successful program. While participation is lower in older women and aboriginal women, the participation rate remains above 65% for most eligible women.
  
  Find out more about the WA Cervical Cancer Prevention Program

For other major cancers the screening story is a little more complicated:

• 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 in its second phase and invites people turning 50, 55 and 65 years of age before 31 December 2010. Therefore eligible people will be those born between:

  • 1 January 1958 and 31 December 1960 = 50 years of age
  • 1 January 1953 and 31 December 1955 = 55 years of age
  • 1 January 1943 and 31 December 1945 = 65 years of age

   

  Read more about the National Bowel Cancer Screening Program.

• Prostate Specific Antigen (PSA) and Digital Rectal Examination (DRE) for prostate cancer.

  There remains controversy over prostate cancer screening. There are high rates of uptake of PSA screening among WA men even though there is no strong evidence that this form of screening meets the WHO criteria (outlined earlier). There has however been an increase in 5 year survival from prostate cancer. This may be due to screening or it may be due to other factors. Men aged 50 and over should talk to their GPs about prostate cancer screening.