British doctors are trialling a "breakthrough" injection that could treat prostate cancer without causing side effects.
The targeted drug, known as topsalysin, is delivered directly into a tumour using magnetic resonance imaging (MRI) and is activated only by a chemical in the prostate known as prostate specific antigen.
As a result, it does not reach surrounding healthy tissue and nerves and could reduce side effects such as impotence and incontinence that are seen with existing treatments.
"This is a fascinating study which uses a state-of-the-art imaging system to track cancer lesions seen on MRI scans and allows injection into the prostate in theatre under ultrasound guidance," said Tim Dudderidge, a consultant urological surgeon at University Hospital Southampton NHS Foundation Trust.
"As the drug is only triggered in the prostate, neighbouring tissue won't be damaged if the drug gets into the wrong place."
Prostate cancer is the most common cancer in men, with more than 46,000 cases diagnosed in the UK every year.
Patients with low-risk cancers often do not require any treatment but are monitored regularly through blood tests and scans, however, those with intermediate or high-risk tumours require intervention.
For large, aggressive tumours this can mean surgery or radiotherapy to treat the whole prostate gland, often resulting in erection and bladder problems.
Although less invasive techniques, such as brachytherapy (small implanted radioactive seeds), cryotherapy (probes used to freeze tumours) or high-intensity focused ultrasound (high-energy soundwaves), provide more targeted treatment, the new injection could "take things to another level".
"We have seen some major developments in prostate cancer treatments in recent years, however, even with the advent of focused ultrasound, patients can still suffer quite serious side effects if the soundwave delivery is even just millimetres off target," said Professor Hashim Ahmed, professor of urology at Imperial College London and the study’s chief investigator.
"This study provides a potential breakthrough as the drug is only activated when inside the prostate and, therefore, could be a truly significant step forward in reducing harmful side effects."
The drug is injected into the prostate between the genitals and the anus, with patients under general anaesthetic or local anaesthetic with sedation for the 30-minute procedure.
Doctors then use biopsy samples combined with MRI images fused with ultrasound images taken with a probe through an image fusion system to ensure they inject the drug into the right part of the prostate.
Mr Dudderidge has treated the first patients in the UK at Southampton General Hospital as part of the trial, which is being run at centres across the UK.
His team, with the help of the Prostate Cancer Support Organisation, will purchase an image fusion system to enable a targeted biopsy service to continue after completion of the study.
Further funds are required to cover the remainder of the cost and anyone interested in supporting through fundraising or donations can do so through Southampton Hospital Charity.
Posted on Tuesday 25 July 2017