Prostate testing may not target those most likely to benefit, warn experts

(Press-News.org) Current prostate specific antigen (PSA) testing “may not effectively target testing to those most likely to benefit, raising concerns about overtesting” warn researchers  from the University of Oxford in a study of over 10 million men across England published by The BMJ today.

Despite UK recommendations to limit PSA testing to patients with symptoms or after discussion with a GP, the results show that many patients are tested more frequently than recommended and repeat testing is occurring in patients without recorded symptoms or with previous low PSA values.

The authors say the findings reflect a lack of consistent international guidance and note that “unpredictable surges in PSA testing, overtesting, and associated costs” may occur as a result of celebrities publicly sharing their cancer diagnoses and advocating for screening.

Prostate cancer is the most commonly diagnosed cancer in the UK, but PSA testing is only routinely recommended for men with certain symptoms. PSA testing generally remains controversial because it has led to an increased number of healthy men being diagnosed and treated unnecessarily for harmless tumours.

Researchers therefore wanted to better understand how PSA tests are used in primary care in England before prostate cancer is diagnosed.

To do this, they drew on data for 10,235,805 men aged 18 and over who were registered at 1,442 general practices across England between 2000 and 2018 and did not have a prostate cancer diagnosis before entering the study.

Data were linked to the National Cancer Registry, Hospital Episode Statistics, and Office for National Statistics and results were analysed by region, deprivation, age, ethnicity, family history of prostate cancer, symptom presentation, and PSA value.

A total of 1,521,116 men had at least one PSA test during the study period, resulting in 3,835,440 PSA tests overall. 

Testing increased fivefold during the study period, particularly in men without symptoms and those with PSA values below recommended thresholds. 

The highest testing rates occurred in men aged 70 and older, who are least likely to benefit from repeat testing, and a substantial portion occurred in men much younger (18-39 years) than recommended.

Testing rates varied by region, deprivation, ethnicity, family history, age, PSA value, and symptoms, with highest rates seen in patients of white ethnicity and in less deprived areas.

Almost half of men (735,750) were retested. Of these, more than 75% had no symptoms recorded and 73% never had a PSA value above the recommended threshold.

The average interval between tests was just over 12 months overall and 17 months for patients who never had a PSA value above the recommended threshold (shorter than most guidelines advise). Once tested, patients had shorter retesting intervals if they were older, belonged to any ethnic group other than white, had a family history of prostate cancer, or had a previously raised PSA value.

The authors acknowledge that using routinely collected primary care data has limitations, and that analyses of retesting intervals were limited to patients with at least two PSA tests during follow-up, raising the possibility of bias. However, they say they comprehensively analysed PSA testing and length of retesting intervals, and results were consistent after further analyses, suggesting they are robust.

As such, they conclude: “PSA testing in primary care is varied. Among patients who underwent multiple tests, many were tested more frequently than recommended, raising concerns about overtesting. PSA retesting is occurring in patients without recorded symptoms or with previous low PSA values.”

“To ensure maximum patient benefit while reducing the risk of overtesting, research is urgently needed to determine appropriate evidence based PSA retesting intervals,” they add.

The major concern raised in this study and similar studies “is that unregulated PSA testing will result in large costs and harms and increase the incidence of prostate cancer likely to remain undetected, while doing little to identify prostate cancer most likely to cause symptoms and death,” say Dr Juan Franco and colleagues in a linked editorial.

They welcome the European Commission’s interest in population based cancer screening including prostate cancer, but say efforts need grounding in high quality evidence gleaned from randomised trials.

This study “highlights the need for better NICE guidance, especially in men outside of recommended ages or men with lower urinary tract symptoms, erectile dysfunction, or other conditions unrelated to prostate cancer,” they conclude. 

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