A new kind of cancer therapy that involves a virus hitching a ride on blood cells to reach tumor sites is showing promising results in clinical trials, researchers said.

This piggybacking or hitchhiking virus called reovirus may be the next weapon in the fight against cancer. What's more these viruses can be administered just like chemotherapy meaning that they can be used against many types of cancer.

The study was conducted on a small group of participants. Some ten people who had advanced bowel cancer were chosen for the study. These people were due to have a surgery to remove tumor that had spread to their livers. They were given 5 doses of viral therapy just days before their surgery.

Blood-tests of the participants showed that the virus was present on the blood cells but was removed by the body a few days later.

Tests done on tumor sites revealed that the virus was active at the tumor sites but not at healthy tissues. Thus the virus specifically attacks the cancer cells and not healthy cells.

Also, reovirus not only attacks the cancer but starts off an immune response in the body that kills off the residual cancer.

"By piggybacking on blood cells, the virus is managing to hide from the body's natural immune response and reach its target intact. This could be hugely significant for the uptake of viral therapies like this in clinical practice," said lead author Professor Alan Melcher from University of Leeds.

"This promising study shows that reovirus can trick the body's defenses to reach and kill cancer cells and suggests that it could be given to patients using a simple injection," said Dr. Julie Sharp, senior science information manager at Cancer Research UK.

Researchers are hopeful that this virus could soon be used to treat cancers.

"We look forward to seeing how this research develops and if this could one day become part of standard cancer treatment," Sharp added.

"It would have been a significant barrier to their widespread use if they could only have been injected into the tumour, but the finding that they can hitch a ride on blood cells will potentially make them relevant to a broad range of cancers. We also confirmed that reovirus was specifically targeting cancer cells and leaving normal cells alone, which we hope should mean fewer side-effects for patients," said Dr. Kevin Harrington from The Institute of Cancer Research.

The study is published in the journal Science Translational Medicine.