Diagnosing prostate cancer too early might cause more harm than good

An mpMRI scan can identify over 90% of men with clinically significant prostate cancer (indicated in this patient by the arrows) that will require treatment, while reducing the detection of cases that do not require treatment. — Datuk Dr TAN HUI MENG

Prostate cancer is the third most common cancer among the male population in Malaysia after colorectal and lung cancer.

However, despite these staggering numbers, prostate cancer screening, compared to breast cancer, appears to be a very controversial topic in medicine.

To date, most health professionals and the public at large are still lost and uncertain as to how to go about preventing and treating prostate cancer.

Sometimes, early prostate cancers are localised and contained within the prostate.

The cancer grows very slowly and may not cause problems for years, or may not even become advanced cancer.

In cases like these, patients do not need to be treated.

The United States Preventive Services Taskforce (USPSTF) gave a Grade C recommendation on screening for prostate cancer.

This means that individuals do not necessarily need to screen for prostate cancer unless they have concerns, which should be discussed with their physicians.

This recommendation came about to reduce the overdiagnosis and overtreatment of prostate cancers.

However, it has resulted in an increasing trend of prostate cancer mortality (death) and morbidity (illness), causing much suffering and compromising the quality of life for patients.

The challenge today is to come up with a strategy to screen the right population to find lethal prostate cancers.

Equally important, we will also need new treatments that are less invasive and cause less disability in individuals.

Improved accuracy

For more than 30 years, the medical profession did not make headway with regard to the diagnosis and management of prostate cancer, other than developing robotic techniques and better radiotherapy to remove the tumours.

Diagnosis using systematic non-targeted transrectal ultrasound scan (TRUS) guided biopsy is highly inaccurate as it has a high false negative rate.

This is dangerous as it misses at least half of prostate cancers.

The transformative advancement in the diagnosis and treatment of prostate cancer was the development of multiparametric magnetic resonance imaging (mpMRI) of the prostate.

Using mpMRI as a form of triage can spare a significant number of men from undergoing unnecessary prostatic biopsies, and avoiding both physical and psychological trauma and morbidity, especially if TRUS biopsies are performed.

Many studies have confirmed that mpMRI is highly reliable in identifying more than 90% of men with clinically significant and lethal prostate cancer.

This method was reported to be much more sensitive (93%) in detecting prostate cancers, compared to TRUS biopsies (48%).

mpMRI also detects much fewer clinically unimportant prostate cancer (54% fewer), compared to using the traditional TRUS biopsy.

In other words, mpMRI reduces overdiagnosis of clinically unimportant prostate cancer and improves the detection of clinically significant and deadly prostate cancer.

To screen or not to screen

Many screening studies have shown that the survival outcome for men diagnosed with prostate cancers, whether they are treated or not, is generally over 10 years or so.

This shows that the majority of men with prostate cancer detected by screening do not benefit from treatment.

Instead, they suffer the consequences of treatment, like losing potency and experiencing urinary or rectal symptoms with occasional incontinence.

However, long-term studies show the benefits of screening after consistent follow-ups for 12 years or more.

The Goteborg Randomised Population-Based Prostate Cancer Screening Trial, done in Sweden, revealed that there was a two-thirds decrease in advanced prostate cancer in men who had undergone over 14 years of follow-up and prostate-specific antigen (PSA) screening, compared to those in the non-screening group.

Therefore, one can conclude that men who have serial PSA screening and then treated if prostate cancer is detected, have a two-thirds less chance of developing advanced prostate cancer, which often results in very painful bone metastases.

There was also a 56% lower mortality rate in the screened population.

Extrapolating from this result, in the Swedish population, PSA screening can save 5,700 out of one million screened men from dying of prostate cancer.

A clearer future

In summary, prostate cancer is still a significant life-threatening disease.

Early detection and early prediction of the disease are crucial, whereas screening in men with long life expectancies is beneficial.

Overdiagnosis and overtreatment issues can be addressed with targeted screening and biopsy only for at-risk patients.

This aims for early detection and diagnosis of localised lethal prostate cancer, which is fully curable.

If diagnosed with non-lethal prostate cancer (especially low-grade cancer), individuals only require good active surveillance with a follow-up mpMRI.

They should also repeat a biopsy of the prostate if necessary.

It is crucial for those with intermediate-grade prostate cancer (ISUP 2) or large volume low-grade prostate cancer (over 6mm core cancer tissue) to receive careful active surveillance, paired with good clinical judgement and a follow-up mpMRI.

Men with localised lethal prostate cancer will need ablative treatment with surgery, radiotherapy, or occasionally brachytherapy.

Counselling for adverse events like erectile dysfunction and occasional urinary incontinence following ablative treatments should also be given.

mpMRI has greatly improved the diagnosis of clinically important prostate cancer, and better genomics will help predict the prognosis of the disease.

Transperineal mpMRI–ultrasound fusion prostatic biopsy is the way forward.

Focal therapy like high-intensity focused ultrasound (HIFU), irreversible electrophoresis or targeted ablation will probably play an increasing role, especially for patients with favourable intermediate-risk or low-grade large-volume prostate cancer.

The future is definitely clearer as both the medical community and the public can be more confident in this era of advanced diagnostics and treatment of prostate cancer, which covers the whole spectrum of the disease.

Datuk Dr Tan Hui Meng is a consultant urologist. For more information, email [e-mail]. The information provided is for educational and communication purposes only, and should not be considered as medical advice. The Star does not give any warranty on accuracy, completeness, functionality, usefulness or other assurances as to the content appearing in this article. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.