Scientists at University College London have made what they believe is a real breakthrough for prostate cancer, long seen as the Cinderella of cancers, using a drug derived from bacteria found at the bottom of the sea, injected into the bloodstream and activated in the prostate by laser beams (The Guardian, 2016).

The treatment has been shown to kill cancerous cells in the prostate without the serious and sometimes life changing consequences of surgery. A radical operation to remove the whole prostate gland risks leaving patients incontinent or impotent. This is why for many years the standard of care has been to operate only on men who are at high risk of the disease progressing and becoming a killer. The rest are assigned to active surveillance. This means regular testing to ensure the cancer is not spreading, but no treatment. Even symptom-free, many men find having prostate cancer psychologically hard to live with.

The study, by Mark Emberton and colleagues published in Lancet Oncology, doesn’t answer all the questions about its future. Mark Emberton said the authors had to find a design for the trial that would satisfy the EMA without having the advantage of technologies that have advanced massively in the last few years. He said “The prostate cancer landscape has been changing so quickly that no trial could keep up with the pace of change.” When they started five years ago MRI scans were not universally available and they had to guess where in the prostate the cancer was. Biopsies are hit or miss.

The researchers focused on four hundred men at low risk and treated half with the therapy, placing optical fibres into the prostate to carry the laser beam. The drug is made from bacteria that live on the ocean floor and are adept at converting any light into high intensity energy, which then kills cancer cells when activated in the prostate without harming normal tissue. The other group were given active surveillance as normal.

At the end of two years, the cancer had progressed in 28% of treated patients compared with 58% of those on active surveillance. Mark Emberton said if they were to do the study now, with the help of MRI scans, they could hit the cancerous parts of the prostate rather than going in blind and the results would be much better. There were side effects, but mostly they had cleared up by the end of the two years. What nobody can know is whether the cancer will stay away, the treated patients will be monitored for years to find out.

Mark Emberton and Prostate Cancer UK think the therapy will be most useful in patients in the grey zone, which is between low and high risk, although for the purposes of the study they had to use patients at low risk. It is not for everyone. Those at very low risk are still better off with no treatment and no side effects.

The idea of a drug made of harmless bacteria that can be activated by light to become cancer killers is not a new one. Photodynamic therapy is already being used to treat skin cancer and others where light can easily penetrate. Mark Emberton said this new technology has been very carefully developed and he believes it could be used to treat other forms of cancer. He hopes it will be approved for use in the NHS as early as possible.