British scientists have developed a new magnetic therapy, which may help to treat prostate cancer.

Scientists previously attempted to treat prostate cancer by injecting white blood cells armed with a virus into the tumor, where they replicate and destroy cancer cells.

However this was not very successful as it was difficult to get the white blood cells, also known as macrophages, to penetrate deep into tumors.

But the new technique, developed by scientists from the University of Sheffield, northern England, uses microscopic magnetic nanoparticles to help direct the "therapeutically armed" macrophages deep into tumors.

Once the cancer cells are infected with the virus, they are destroyed and the multiplying virus spreads to attack neighboring prostate cancer cells.

The treatment involves placing magnetic particles into the macrophages, then moving them with an external magnet. It helps to ensure the macrophages are delivered directly to the prostate cancer cells, leaving healthy cells unharmed.

The authors, who presented their findings at a national cancer research conference in Liverpool, northern England, said, "This magnetic targeting approach could be used to increase the efficacy of various cell-based gene therapies for cancer."