Promising new research looks to improve prostate cancer diagnosis

II  JAN 23 2017

Lewis Germain

Cancer of the prostate is the most common cancer amongst men in the UK, making up just over a quarter. Some cause symptoms, some do not; some require treatment, some are of little significance and can be left alone (what we call ‘subclinical’ prostate cancer). However, despite the frequency with which prostate cancer occurs, the process of diagnosis is one that we have struggled to improve. In this process, samples of the prostate are taken – a biopsy –  which is unpleasant, risky and not always accurate: a lot to endure if the results are negative. This investigative process could be about to change, though, as new research published in a prominent medical journal has shown the benefits of a new, non-invasive scan.

Diagnosing Prostate Cancer

Currently, the process of diagnosing prostate cancer is largely dependent on the history of symptoms, examination of the prostate gland, and a marker in the blood called Prostate Specific Antigen, or PSA (a raised level could indicate cancer, but is usually something less worrying). If, after each of these factors has been considered, the patient is deemed to be at risk of having prostate cancer, they are sent for a biopsy. If the biopsy suggests that cancer is present, the ‘grade’ of the cancer will be determined according to how abnormal the cells look. Based on this, as well as how far the cancer has spread (the ‘stage’), treatment options are decided upon.

Problems with the current diagnostic pathway

As previously stated, the current pathway has its disadvantages. Firstly, a prostate biopsy is an uncomfortable procedure that carries potential complications. These can include:

  • Bleeding
  • Infection
  • Blood in the urine
  • Blood in the semen
  • Difficulty urinating
  • Erectile dysfunction

Secondly, the accuracy of the biopsy is not as good as we would like. As we don’t know the specific site of any prostate tumour, the biopsy may miss it: about 1 in 5 aren’t picked up. Also, biopsies can detect the subclinical cancers mentioned previously. This can lead to patients and families enduring unnecessary worry and, potentially, unpleasant treatments with little benefit to them. This flawed process is desperate for improvement.

New research findings

However, new research involving 576 men has proposed a new pathway for diagnosis. This would involve a triage system, where men who were judged to be at risk of having prostate cancer by their doctors would receive a high-powered scan called an MP-MRI instead of a biopsy. If this scan suggests that cancer is unlikely, no further test would be needed at that time. If cancer is likely, a biopsy would then be performed.

Study statistics simplified

The primary aim of these findings is to reduce the number of men who require a biopsy, but is the scan reliable enough to do this? The statistics, which are as follows, would suggest that it is.

The scan:

  • Picks up 9 out of ten cases of prostate cancer (93%)
  • If negative*, is correct 9 times out of ten (89%)


There is a downside, though. The scan does tend to over-diagnose:

  • Of those with a positive** scan, only half actually had prostate cancer
  • 2 out of 5 patients without prostate cancer still had a positive scan


   *Negative scan = cancer deemed unlikely
**Positive scan = cancer deemed likely and more tests needed

Men with a positive scan would then go on to have a biopsy to confirm or exclude the cancer. Nevertheless, it is important to focus on the first two bullet points: most cancers are picked up, and most negative scans are correct. This means that, rather than everybody undergoing a biopsy, the scan can prevent some of those who probably don’t need one from doing so unnecessarily.

Will this take effect soon?

These findings are relatively new, so if the proposed system is implemented by the NHS, it will not be straight away: they are currently analysing if it would be cost-effective to do so. Nevertheless, these findings are promising, and improvements to how suspected prostate cancer is investigated may not be too far away.

Any opinions above are the author's alone and may not represent those of the NHS or Mind and Medicine. Any comment is based on the best available evidence at the time of writing. All data is based on externally validated studies unless expressed otherwise. Novel data is representative of sample surveyed. Online recommendation is no substitute for seeing your own doctor and should not be taken as medical advice.


References
http://www.bbc.co.uk/news/health-38665618

Ahmed HU, El-Shater Bosaily A, Brown LC et al (2017). Diagnostic accuracy of multi-parametric MRI and TRUS biopsy in prostate cancer (PROMIS): a paired validating confirmatory study. The Lancet; (Corrected proof, Ahead of publication).

Mejak SL, Bayliss J, Hanks SD (2013). Long Distance Bicycle Riding Causes Prostate-Specific Antigen to Increase in Men Aged 50 Years and Over. PLoS One; 8(2): e56030. Doi:10.1371/journal.pone.0056030.

http://patient.info/health/prostate-specific-antigen-psa-test

http://www.mayoclinic.org/tests-procedures/prostate-biopsy/details/risks/cmc-20200186

http://patient.info/doctor/prostate-cancer-pro

https://pathways.nice.org.uk/pathways/prostate-cancer#path=view%3A/pathways/prostate-cancer/prostate-cancer-overview.xml&content=view-index

http://www.nhs.uk/Conditions/Cancer-of-the-prostate/Pages/Diagnosis.aspx