Pharmacy and PSA testing: troublesome bedfellows?

 

ABOUT 26% of all new cases of cancer in men is prostate cancer – it is the most common cancer in men, and is the second most common cause of cancer death in males in the UK (after lung cancer), accounting for 13% of all cancer deaths, with 11,500 men dying of it every year1.

Clearly, we need to tackle this, and some pharmacies believe they are helping.

A pharmacy proudly displays its new professional service, PSA testing, on social media with the following words:

  • Men over 50 are at increased risk of prostate cancer.
  • Over 40,000 men per year are diagnosed with prostate cancer.
  • Early detection of prostate cancer may lead to better treatment outcomes.
  • A PSA test can give you an idea about whether you may have prostate cancer before any symptoms develop.
  • £10.99.

But, there’s just one problem.

And it’s a massive problem for a science-based profession that needs to consider whether the evidence shows that the benefits of an intervention outweigh the harms.

You see, while there was a study, the European Randomized Study of Screening for Prostate Cancer (ERSPC), that seemed to show that prostate screening can reduce cancer deaths by 21%2 – a very significant opportunity — a Cochrane systematic review3 of five randomised controlled trials (RCTs, n=341,342), which included the data from the ERSPC, concluded that prostate cancer screening did not reduce prostate cancer specific mortality or overall mortality.

Quite simply, the PSA test is not good enough at identifying those who have prostate cancer and those who do not. In addition, it is unable to make a distinction between fast-growing cancers and slow-growing cancers that may not cause symptoms in the man’s lifetime, or impact on their lifespan (only 16% of US prostate cancer patients die from the disease)4.

So unreliable is the PSA test that the Public Health England (PHE) Prostate cancer risk management programme: benefits and risks of PSA testing specifically says “GPs should not proactively raise the issue of PSA testing with asymptomatic men.”5

In fact, Richard Ablin, the man who discovered PSA in the 1970s, has described PSA testing as a “profit-driven public health disaster”6.

So, why are pharmacies doing this? Why are they selling an £11 test that, in the discoverer of PSA’s own words “can’t detect prostate cancer and, more important[ly]… can’t distinguish between the two types of prostate cancer — the one that will kill you and the one that won’t”.

The decision to take a PSA test should not be taken lightly, and should only happen after consideration of the risks, benefits, and limitations5.

PHE has produced an information pack to help primary healthcare professionals counsel asymptomatic men aged 50 and over who proactively ask about PSA testing for prostate cancer. Note “proactively”. A man responding to a pharmacy advert for PSA testing does not fall within this category.

“The decision about whether a man takes a PSA test is a complex one and has to be thought through carefully.

“There are potential harms as well as benefits in taking the test and we know that many men really appreciate the opportunity to discuss the test with their GP.

“Our new information pack will make it easier for GPs to have this conversation with their patients, and assist men in making a decision that is right for them,” explains Dr Anne Mackie, PHE’s Director of Screening7.

To get an idea of the harms associated with false positives from PSA testing it’s important to understand the diagnosis and management of prostate cancer.

Diagnosis
A normal prostate-specific antigen (PSA) level ranges from 0–4 nanograms/mL. Men with a PSA of over 3 nanograms/mL will need further investigation and consideration of risk factors5:

  • Prostate size.
  • Digital rectal examination (DRE) findings.
  • Age.
  • Ethnicity.
  • Family history of prostate cancer.
  • Body weight/BMI.
  • Co-morbidities.
  • History of any previous negative biopsy.
  • Any previous PSA history.

However, this upper level of normal may vary according to age and race and there can be other reasons for raised PSA (infection for example). Men with an elevated PSA may need further investigation, for example a digital rectal examination (DRE), a transrectal ultrasound (TRUS), or a biopsy8.

However, 3 in 4 men with a raised PSA will not have prostate cancer, and this low specificity of the PSA test has led to harms of overdiagnosis and overtreatment in up to 50% of men5.

The DRE involves the GP feeling the prostate through the rectum for any irregularities. It can be embarrassing and uncomfortable, but is not usually painful. A negative DRE does not exclude prostate cancer.

TRUS, where a small probe is inserted into the rectum, can determine the size of the prostate, but again, it is not reliable enough to exclude prostate cancer.

A biopsy is usually guided by ultrasound and involves taking 10-12 core sample of the prostate gland – this process also approaches the prostate through the rectum. Adverse effects include bleeding, pain, or infection8.

Treatment8
Management options for prostate cancer include radical prostatectomy (surgery to remove the prostate gland), or radiotherapy in addition to palliative and adjunctive treatments (for example androgen withdrawal or blockade).

Adverse effects of these methods include pain, erectile dysfunction as well as urinary and bowel complications. Adverse effects of hormonal treatments include erectile dysfunction, loss of libido, breast swelling, hot flushes, and osteoporosis.

In 2016, the ProtecT trial reported the results of a RCT where 1,643 men aged 50-69 with a diagnosis of localised prostate cancer were randomised to one of three arms – ‘active monitoring’ (where treatment was delayed and cancer progression was monitored principally via the use of PSA testing), radical prostatectomy or radiotherapy. After a median of 10 years of follow-up, there was no difference in either all-cause mortality or prostate cancer-specific mortality between groups9.

Risk factors for prostate cancer8

  • Increasing age — it is largely a disease of older men. By the age of 80 years, 80% of men will have evidence of prostate cancer.
  • Black ethnicity — men of black ethnicity are at highest risk of developing prostate cancer and are also twice as likely to die of the disease.
  • Family history of prostate cancer — the lifetime risk of developing prostate cancer is 8%, but increases depending on the number of relatives affected and the age at which they were diagnosed.
  • Obesity — men have a 15–20% increased risk of dying from prostate cancer with every 5 kg/m2 increase in BMI.

 

Benefits of PSA testing8

  • Early detection — PSA testing may lead to prostate cancer being detected before symptoms develop.
  • Early treatment — detecting prostate cancer early before symptoms develop may extend life, or facilitate a complete cure.
     

Limitations and risks8

  • False-negative PSA tests — about 15% of men with a negative PSA test may have prostate cancer, but it is not known what proportion of these cancers become clinically evident.
  • False-positive PSA tests — about 75% of men with a positive PSA test have a negative prostate biopsy but will have been worried unnecessarily by the results of the test.
  • Unnecessary investigation — a false positive PSA test may lead to invasive investigations, such as prostate biopsy, and there may be adverse effects (for example bleeding, or infection).
  • Unnecessary treatment — a positive PSA test may lead to radical treatment of prostate cancers which would not have become clinically evident in the man’s lifetime. Adverse effects of treatment are common and serious, and include urinary incontinence and sexual dysfunction.

We need to get better at diagnosing clinically important prostate cancer in men, but promoting PSA testing and offering it to asymptomatic men isn’t the way to do it.

Despite this, pharmacies continue to offer screening tests inappropriately and it is entirely reasonable to enquire why this is the case. Is it because pharmacists are ignorant of the evidence in this area? Have pharmacists, just like Michael Gove, had enough of experts? Are pharmacists wilfully stocking and promoting PSA tests in order to generate profit, or is this another example of pharmacy contractors allowing a profit motive to dominate evidence-based pharmacy practice?

Whatever the answer, this is just another example of where we need to do better and consider the implications for our profession.

Dr Joseph Bush is a Senior Lecturer in Pharmacy Practice at Aston University*
Ross Ferguson is a clinical author, pharmacy and healthcare writer

*writing in a personal capacity

References
1. Cancer Research UK. 2014.
2. Schroder FH, et al. Screening and prostate cancer mortality: results of the European Randomised Study of Screening for Prostate Cancer (ERSPC) at 13 years of follow-up. Lancet. 2014;384:2027–2035. doi: 10.1016/S0140-6736(14)60525-0.
3. Ilic D, Neuberger MM, Djulbegovic M, Dahm P. Screening for prostate cancer. Cochrane Database of Systematic Reviews 2013, Issue 1. Art. No.: CD004720. DOI: 10.1002/14651858.CD004720.pub3.
4. Epstein MM, Edgren G, Rider JR, Mucci LA, Adami HO. Temporal trends in cause of death among Swedish and US men with prostate cancer. J Natl Cancer Inst. 2012;104:1335–42.
5. Public Health England (PHE) guidance Prostate cancer risk management programme (PCRMP): benefits and risks of PSA testing. 2016.
6. Ablin, RJ. The Great Prostate Mistake. The New York Times. 2010
7. Public Health England. Updated guidance for GPs on PSA testing for prostate cancer. 2016.
8. NICE Clinical Knowledge Summaries: Prostate cancer. 2017.
9. Hamdy FC, Donovan JL, Lane JA, et al.10-year outcomes after monitoring, surgery, or radiotherapy for localized prostate cancer. N Engl J Med. 2016;375 (15):1415–1424.

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