In a breakthrough, U.S. doctors claim to have wiped out a woman’s advanced blood cancer with a massive dose of the measles vaccine, enough to inoculate 10 million people.

The woman was part of a clinical trial at the Mayo Clinic demonstrating that cancer cells can be killed with injections of a genetically-engineered virus through a process known as virotherapy.

Two patients in the study received a single intravenous dose of an engineered measles virus (MV-NIS) that is selectively toxic to myeloma plasma cells.

Stacy Erholtz, 49, from Minnesota, was one of the two patients in the study who received the dose last year, and after ten years with multiple myeloma has been clear of the disease for over six months.

“It was the easiest treatment by far with very few side effects. I hope it’s the future of treating cancer infusion,” Erholtz was quoted as saying by KARE-11.

Multiple myeloma is a cancer of plasma cells in the bone marrow, which also causes skeletal or soft tissue tumours.

This cancer usually responds to immune system stimulating drugs, but eventually overcomes them and is rarely cured.

“We have known for some time viruses act like a vaccine. If you inject a virus into a tumour you can provoke the immune system to destroy that cancer and other cancers,” said Dr. Steven Russell, a Mayo Clinic haematologist, who spearheaded the study.

“This is different, it puts the virus into bloodstream, it infects and destroys the cancer, debulks it, and then the immune system can come and mop up the residue,” Dr. Russell said.

Two multiple myeloma patients were chosen because they are immune-compromised, and can’t fight off the measles before it has time to attack cancer.

Both had limited previous exposure to measles, and therefore fewer antibodies to the virus, and essentially had no remaining treatment options.

Of the two subjects in the study, Stacy was the only to reach full remission. The other patient’s cancer returned after nine months.

However, imaging studies of the second patient provided a clear proof that the intravenously administered virus specifically targeted the sites of tumour growth.

This was done using high-tech imaging studies, which were possible only because the virus had been engineered with a ’snitch gene’ — an easily identifiable marker — so researchers could accurately determine its location in the body.

Researchers are now moving into a phase two clinical trial involving more patients with a goal of US Food and Drug Administration (FDA) approval within four years.

The findings were published in the journal Mayo Clinic Proceedings.