Pearls and Irritations

Australia has the highest  rate for cancer according to the World Cancer Research Fund[1].  At 468 /100,000 we are 7% ahead of NZ (who have 438), 33% ahead of the US (352), 40% ahead of Canada (334), 47% ahead of the UK (319), 59% ahead of Sweden (295) and 89% ahead of Japan (248)[2].  It might also be noted that Australia has gone from a rate of 383 in 1982 to 468 in 2019, a 22% increase.

This worrying fact seems to have been largely overlooked in the major media, but it should be a cause of major investigations and inquiry!

The first question should be what factors are causing the cancers and can any of them be reversed?

One of the causes of cancer is radiation- there is a background level and Australia has more sunlight than most, but what are the other causes of radiation of the population?

One of the world’s largest studies, from the University of Melbourne  of 0-19 year olds using Medicare statistics showed that a single CT increased the risk of any cancer by 24% and this increased another 15% for each subsequent CT[3]. If the lifetime risk of cancer is 1 in 5, and increases 24%, it becomes 1 in 4, which at a population level is highly significant.

Putting aside the high cost of treatment, according to the US FDA there will still be 1/2000 chance of fatality from a single radiological examination with an effective dose of 10 millisieverts[4].  Doses from common CTs are Spine 6 millisieverts, Chest 7, Abdomen 8, Coronary Angiogram 16, Whole Body 20[5].

A study by Kalra found that the estimated risk of cancer death for those undergoing abdominal CT is approximately 12.5 /10,000[6].  But follow up protocols for many tumours involve quarterly CTs and whole body screening CTs are now standard in many EDs.

When CT machines were introduced, the Federal Government licenced them, making them an investment being paid off by their use.  This created an incentive for more scans and scanners.  It was very short term and expensive solution.

Australia has more CT machines than any other country in the world with 67 per million population in 2018, with NZ at 16, the US 44, Canada 12, the UK 9.5[7].

When the MRI became freely available and proved it itself to be a better and more sensitive modality for Neuro, Musculo-Skeletal and soft tissue organs, the government was not going to make the same financial mistake, so only allowed MRIs to be licenced in small numbers.  CTs continue to dominate the radiological diagnostic practices since the 1990s with seemingly little knowledge or concern about the consequent radiation doses to the population.

Part of the restrictions on MRI ordering was to stop GPs ordering MRIs on Medicare, though GPs can order CTs.  The diagnostic sequence then becomes a visit to a GP, a CT, a specialist referral, the specialist orders an MRI, and a second visit to the specialist to get the result and advise.  Clearly if the GP were to order the MRI and make a decision, it would save the CT and two specialist visits which would lead to a large saving.  Depowering GPs has increased medical costs and unnecessarily irradiated the population.

The use of CTs also continues in areas where they are not effective.  CTs are currently used to diagnose stroke, but have a false negative rate of 83 to 90%, whereas a 90 second MRI has a diagnostic confidence rate of over 99%.  MRIs do not have to be ‘tunnel machines’ and can be ‘multipositional Open units’, diagnosing individual body parts, replacing X-rays in limb fractures in Emergency Depts, or even have mothers holding their infants while they are scanned, helping immensely in managing children without anaesthetics or radiation dangers.

It might be noted that a Western Australian survey in 2014 showed that 73% of CTs were provided in private settings, some are MBS subsidised, but it is difficult to get exact numbers of CTs performed.  It was also noted that the levels of knowledge of the radiation risk of CTs was not good[8].  Patients are rarely informed of the risks and cost-benefits and rarely sign consents.

Australia needs a concerted effort by governments to increase the number and variety of MRI machines and phase out CTs.  The Federal Governments discouragement of MRIs may be a very significant factor in Australia’s world-leading cancer rate and this needs to be addressed as a matter of urgency.

We should aim to have ZERO radiation risk in medical radiology, especially when this is now available.  Australia has 14 MRI scanners per million population whereas the USA has 40 and Japan 56[9].

 Dr Arthur Chesterfield-Evans is an anti-tobacco campaigner, ex-politician and current GP.

[1] [1] www.wcrf.org/dietandcancer/cancer-trends/data-cancer-frequency-country

[2] http://worldpopulationreview.com/countries/cancer-rates-by-country/ Sept 2019

[3] Mathews JD, Forsythe AV, Brady Z, et al. British Medical Journal 2013 May 21; 346:f2360

(data study of 11 million Australians under age of 19 years, with no cancer diagnosed at least 1 year after time of exposure to a CT scan and with the mean duration 9.5 years follow-up after exposure to the CT scan)

[4] www.fda.gov/Radiation-emittingProducts/RadiationEmittingProductsandProcedures/MedicalImaging/MedicalX-Rays/ucm115329.htm

[5] https://www.health.harvard.edu/cancer/radiation-risk-from-medical-imaging

[6] Kalra MK, Maher MM, Toth TL, et al. Strategies for CT Radiation Dose Optimization, Radiology 2004 March, Vol 230

[7] https://data.oecd.org/healtheqt/computed-tomography-ct-scanners.htm

[8] Gibson D, Moorin R, D’Arcy J Holman C, Cohort study of Western Australia computed tomography utilisation patterns and their policy implications  www.ncbi.nlm.nih.gov/pmc/articles/PMC4226860/

[9] https://data.oecd.org/healtheqt/magnetic-resonance-imaging-mri-units.htm#indicator-chart

[10] www.westernsydney.edu.au/nanoscale/nanoscale_organisation_and_dynamics/symposium_on_mri_and_diffusion

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