A cancer vaccine in the form of an implant is the first to successfully eliminate tumors in mammals, according to a new study.

The new approach, pioneered at Harvard University, uses plastic disks implanted under the skin to reprogram the immune system to attack tumors.

The implants are the size of a small fingernail and they release chemicals that attract a specific type of immune cells.

When these cells move to the implant they are programmed to prime the rest of the immune system to attack and kill cancer cells.

While the system worked on tumours in mice, researchers say the implant will need modification before it can be tested in people, but this new proof of principle they say, is an important first step.