New injection could stop impotence and incontinence in men receiving prostate cancer treatment

• Topsalysin is injected into tumours but leaves surrounding tissue and intact 
• Drug is currently being trialled by doctors and is being hailed as breakthrough
• Doctors say drug could help thousands of men without the risk of side effects
• Prostate cancer is most common cancer in men, with more than 46,000 diagnosed in the UK each year 

A new injection could spare men the side effects of prostate cancer treatment, such as impotence and incontinence.

The drug, being trialled by British doctors, is injected into tumours to kill them, but leaves surrounding healthy tissue and nerves intact.

Called topsalysin, it is being hailed as a major breakthrough in treatment of the disease.

Most existing treatments carry a high risk of damaging healthy tissue surrounding the tumour. But the smart drug is activated only by the presence of a chemical called prostate specific antigen, found only in the prostate.

Doctors say the drug could help thousands of men without the risk of devastating side effects.

‘This is incredibly exciting because we can now deliver a drug which is only active in the prostate, and will not damage nerves, the rectum or bladder,’ says Tim Dudderidge, consultant urological surgeon at University Hospital Southampton NHS Foundation Trust, who treated the first UK patients on the multi-centre study.

Prostate cancer is the most common cancer in men, with more than 46,000 diagnosed in the UK each year. 

In many cases, the cancer is low-risk and men are simply offered regular blood checks or scans.

Others are offered surgery or radiotherapy to treat the whole prostate. But treatment can damage nerves, muscles and the rectum.

Half of men end up with erection problems and up to 20 per cent have urine leaks – although both problems can settle down within 18 months of treatment.

Less radical treatments include brachytherapy (which uses small implanted radioactive seeds), cryosurgery (to freeze the tumour) or high-intensity focused ultrasound (HIFU), where a beam of high-energy soundwaves is fired into the body to destroy malignant cells.

But even targeted treatments such as HIFU can have serious consequences if the soundwaves are even millimetres off target.

Earlier studies carried out at University College London Hospital found topsalsyin killed cancer cells in about half of men with low-to-intermediate-risk prostate cancer, and there were no significant side effects.

The drug is injected into the prostate through the area between the genitals and the back passage. Patients have a general anaesthetic, or a local anaesthetic with sedation, for the 30-minute procedure. Doctors use MRI images and biopsy samples, fused with ultrasound images, relayed via a probe in the rectum, to ensure they inject the drug into the right part of the prostate.

The drug is delivered using two or three long needles to reach the prostate, a few inches inside the body.

Mr Dudderidge says: ‘The prostate is situated in a tricky part of the body. What makes this new drug so attractive is that it is activated only in the gland.’

He adds: ‘It’s potentially ground-breaking. This drug could be a massive step forward in the reduction of side effects.’