May was awash with news stories about blood tests for prostate cancer. Reports that a new serum test called IsoPSA could predict prostate cancer more precisely than conventional PSA testing brought obvious interest. The new test, studied at five centres in the US, measures structural changes in PSA rather than concentration. There are early indications that this provides a much better prediction of overall prostate cancer risk, and the risk of clinically significant cancer.
But the research is at an early stage. Another story about a prostate cancer blood test grabbed fewer headlines, but is arguably of more significance. The Annals of Oncology reported a European multi-centre study by researchers investigating biomarkers which predict how well men with advancing prostate cancer will respond to the new hormone therapies abiraterone and enzalutamide.
These treatments can control prostate cancer for many years in men who no longer respond to traditional hormone therapy. But they have no effect in some men and the cancer rapidly returns. The European researchers believe they have found a blood biomarker which predicts whether a patient will respond or not to the drugs, potentially preventing thousands of men from receiving unnecessary treatment – and the risk of side effects such as fluid retention, high blood pressure and liver problems.
Both stories are important. But while the world is aware of PSA testing, and the search for better successors, it knows far less about the many other fronts on which the use of blood biomarkers is being refined, and is relatively unaware that the search for ever-more accurate and reliable markers – to detect the disease early, to distinguish “tiger” tumours from “pussycats”, and to target treatments after diagnosis – is at the heart of hopes to advance prostate cancer survival.
Clinicians working in prostate cancer know that the challenge is not only to diagnose the disease early. For the thousands of men with advanced prostate cancer, there is an urgent need to extend life with good quality. And it is here that biomarkers provide perhaps greatest hope.
When I recently spoke to leading prostate specialist Silke Gillessen for Cancer World, the Swiss medical oncologist told me that finding better markers had to be the research priority in advanced prostate cancer. We need biomarkers which predict whether tumours are likely to respond to hormone drugs, or chemotherapy, or PARP inhibitors. Eliminating unnecessary treatments reduces time wasted as well as side effects.
We need markers to identify the high-risk cancers that will require multi-modality treatment – and the lower risk cancers, where just one treatment may be enough. And we need predictive factors identifying which targetable mutational changes drive disease.
Predictive blood tests aren’t as glamourous as new treatments. They certainly don’t draw as much research funding or industrial investment. But clinicians working in prostate cancer know the immense impact that advances in this field could have.