Could a ‘manogram’ for prostate cancer replace invasive test?

The blood tests have come back. “Hmm, one of these is elevated”, your doctor says. “I think it’s best if you have some further investigations.”

I suspect I’m not the only patient whose immediate thought at this point is to hope there is a non-invasive investigational option. The words “X-ray” or “ultrasound” have a sweet ring to them at times like this.

However, any recommendation containing the word biopsy may cause your heart to sink.

Take prostate cancer as an example. If a blood test for prostate specific antigen (PSA) is significantly elevated, referral to a urologist is likely to involve a discussion about Trus. Having a Trus (transrectal ultrasound guided) biopsy is the standard procedure following a raised PSA reading. It involves inserting an ultrasound probe into the rectum and then, guided by the ultrasound images, inserting a fine needle along the probe, through the rectum wall and into the prostate, to remove a tissue core. This is repeated about 12 times as the doctor takes samples from different prostate areas.

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It can be a painful experience.

Just because you have an elevated PSA does not mean you have prostate cancer

Brian Kavanagh, chairman of the patient advocacy group Men against Cancer, says he fainted as he left hospital after the Trus. He told Cancerworld, the journal of the European School of Oncology, the experience was "excruciating" and "medieval". A few days later, he was re-admitted with septicaemia, a bloodstream infection caused by the biopsy. It took him three months to shake it off.

The prostate is a walnut-sized gland that sits at the base of the bladder and surrounds the urethra – the tube that runs from the bladder to the penis. About 75 per cent of men in their 70s have urinary symptoms that are caused by a benignly enlarged prostate. Meanwhile, more than 3,000 men are diagnosed with prostate cancer in Ireland every year.

Just because you have an elevated PSA does not mean you have prostate cancer and so the test is not suitable as a screening test. And the decision to monitor or treat an early-stage cancer is not straightforward. One major study followed patients for 10 years and found no difference in death rates between men who were picked at random to have surgery or radiation, and those whose cancer was “active monitored”. In addition, death rates from the cancer were low overall: only 1 per cent of patients were dead 10 years after diagnosis.

Evidence

With all this uncertainty, and the unpleasant nature of a Trus biopsy, an alternative, non-invasive test was badly needed. Thanks to a number of studies, including the PROMIS trial, it looks like we now have a viable alternative. There is compelling evidence that carrying out multiparametric MRI (mpMRI) scans before biopsy is an effective way of detecting the presence of prostate cancer. It also provides highly accurate guidance for a subsequent biopsy if the scan does identify suspicious lesions.

The PROMIS trial, involving 740 men with clinical suspicion of prostate cancer and no previous prostate biopsy, tested whether an mpMRI scan before biopsy could identify men who might safely avoid the invasive test. It found that using mpMRI to triage men might allow more than one in four men referred on suspicion of prostate cancer to avoid a primary biopsy. And if subsequent Trus biopsies were finely tuned by the mpMRI findings, up to 18 per cent more cases of clinically significant cancer might be detected.

In December 2018, the British National Institute for Health and Care Excellence (Nice), recommended mpMRI as the first-line investigation for people with suspected clinically localised prostate cancer. It seems the non-invasive test is set to become the gold standard.

Looking forward, could the MRI test replace PSA and ever become a “manogram”, the male equivalent of a mammogram? It seems unlikely – let’s just be happy an alternative to the sometimes barbaric Trus has been found.

mhouston@irishtimes.com