Rates of prostate cancer across Europe since 1980 are "indicative of overdiagnosis", say researchers in a study published by The BMJ today.
Overdiagnosis refers to the detection of harmless cancers that are unlikely to cause symptoms or death during a patient's lifetime, which can lead to unnecessary treatment, negative impacts on quality of life, and wasted healthcare resources.
The findings show rapid increases in the number of new cases (incidence) in parallel with uptake of so far predominantly opportunistic prostate specific antigen (PSA) testing. Yet death rates during 1980-2020 were much lower and less variable, with steady declines in most countries and fewer differences between countries.
This divergence between incidence and deaths "suggests that the intensity and coverage of PSA testing has been a critical driver for the increasing trends in prostate cancer incidence in Europe," say the researchers, which reinforces the need to minimise harms of overdiagnosis.
This is of particular relevance for the potential implementation of population-wide prostate cancer screening programmes, which, if implemented in the future, should be carefully designed and planned to minimise and monitor the harms of overdiagnosis in the population, they add.
Unregulated and opportunistic PSA testing has been, and still is, common in Europe. The EU Beating Cancer Plan recently proposed a new strategy for prostate cancer screening programmes, but baseline data on national levels and trends in prostate cancer outcomes are needed before new approaches are introduced.
To do this, researchers obtained data on annual incidence rates of prostate cancer for men aged 35-84 years in 26 European countries from 1980-2017 and mortality data from 1980-2020. They also carried out a review of studies on uptake of PSA testing across 12 European countries.
They found that incidence more than doubled in most countries from 1990 to 2017, in parallel with uptake of PSA testing, although the pace of increase varied greatly across countries and over time.
For example, increases in incidence were highest in northern Europe, France, and the Baltic countries, notably in Lithuania where rates increased up to eightfold. The difference between the highest and lowest incidence rates across countries ranged from 89.6 per 100,000 men in 1985 to 385.8 per 100 000 men in 2007.
In contrast, death rates were much lower in absolute terms, spanning from 12 (Ukraine and Belarus) in 1981 to 53 (Latvia) deaths per 100,000 men in 2006. The difference between the highest and lowest death rates across countries ranged from 23.7 per 100,000 men in 1983 to 35.6 per 100,000 men in 2006.
Considering all countries and periods, there was up to a 20-fold variation in prostate cancer incidence, but only a fivefold variation in deaths.
This is an observational study so no firm conclusions can be drawn about cause and effect, and the researchers point to several limitations that mean the findings should be interpreted with caution.
Nevertheless, they say these results "should help to improve the understanding of the effect of PSA testing on incidence and mortality in Europe by highlighting consistent patterns across countries."
"The current high incidence of prostate cancer in many countries may be inflated by unregulated and opportunistic PSA testing that serves to mask any variations due to causal factors and may be indicative of overdiagnosis," they explain.
"Careful monitoring and assessment of the benefits and harms, including overdiagnosis, will be essential for the potential implementation of EU guidelines and the prospective introduction of population-wide prostate cancer screening," they add.
