Are prostate cancer-specific mortality rates in Australia higher than they should be?

An article just published in the World Journal of Urology has suggested that rates of prostate cancer-specific mortality in Australia seem to have been unexpectedly higher than in the USA.

Feletto et al. set out to compare the incidence and mortality rates for prostate cancer in Australia, USA, Canada, and England over a 17-year time frame (from 1994 to 2010) and to quantify the gap between observed prostate cancer deaths in Australia and expected deaths, using US mortality rates. The study was based on the premise that since the four countries have similar degrees of development any differences in prostate cancer mortality rates should have more to do with the timing of widespread introduction of screening for prostate cancer than with efficiencies in the treatment of prostate cancer or other factors.

Here are the core study findings reported by the authors:

  • Prostate cancer incidence rates initially peaked, in all four countries, between 1992 and 1994.
  • A second, higher peak in incidence rates occurred in Australia in 2009 (to 188.9 cases per 100,000).
  • Prostate cancer-specific mortality rates (based on the age-period-cohort or APC model) decreased more slowly in Australia than in the three other nations.
    • Australia, 1997 to 2011 — mortality rate decline  = −1.7 percent
    • USA, 2004 to 2010 — mortality rate dceline = −2.9 percent
    • Canada, 2006 to 2011 — mortality rate decline = −2.9 percent
    • England, 2003 to 2008 — mortality rate decline =  −2.6 percent
  • In 2010, mortality rates were highest in England and Australia (at 23.8 per 100,000 in both countries).
  • The mortality gap between Australia and USA grew from 1994 to 2010, with a total of 10,895 excess prostate cancer deaths in Australia compared with US rates over 17 preceding years.

Feletto et al. conclude that:

Prostate cancer incidence rates are likely heavily influenced by prostate-specific antigen testing, but the fall in mortality occurred too soon to be solely a result of testing. Greater emphasis should be placed on addressing system-wide differences in the management of prostate cancer to reduce the number of men dying from this disease.

Exactly why one should see a significantly higher prostate cancer-specific mortality rate in Australia compared to the USA over this time period is hard to determine. While timing of the introduction of PSA screening may be a factor, there may be other relevant factors of several types, including issues of ethnicity, access to specialty care, diet, etc.

It is also worth noting that the very high proportion of white Australians with British origin may help to explain why the prostate cancer-specific mortality rates in England and Australia have become similar. There may be genetic and other ethnic factors here that are relevant.

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