Bacteria, lasers, and prostate cancer

by Kevin Turner

Prostate cancer drug based on sea-bed bacteria brings complete remission for half of patients
— Daily Telegraph 20/12/2016

This headline was typical of the way in which a preliminary research study was reported. This is exciting work. A light sensitive drug is injected into a patient with prostate cancer, and then fibres that emit a laser light are inserted into the prostate. The light switches on the drug, and the drug kills prostate cancer cells. And it seems to work - at least in some patients. We need new treatments for prostate cancer - treatments that have fewer side effects than current treatments. And this treatment shows some promise. Unfortunately though, the reporting of this preliminary research made it sound as if this is a major, proven advance. It's not. All the patients treated had very low risk prostate cancer - the kind of disease that urologists wild generally watch, rather than treat (known as Active Surveillance). And of those low risk patients, only half were free of cancer at the end of the treatment period, and in nearly one third of patients the disease seemed to get worse. The side effect profile wasn't that impressive either - with one third of patients developing erectile dysfunction. Unfortunately the hype was not supported by the published results. Some promise, yes. But a major new advance? No, it's a long way from that.