One clinical trial shows that thousands of people with head and neck cancer may live longer without cancer due to immunotherapy drugs.

The scientists behind the study said this is the first sign of a breakthrough in 20 years of difficulty in treating cancer patients.

Laura Marston, 45, of Derbyshire, felt "surprisingly she's still here" after being diagnosed with advanced tongue cancer six years ago.

She received immunotherapy before and after the surgery, and researchers say if the cancer recovers.

It is well known that cancers in the head and neck are difficult to treat, and there is little change in the way patients are treated within twenty years.

More than half of the people died within five years.

Laura has only a 30% chance of surviving long after her diagnosis in 2019, because the ulcers on her tongue won't go away.

The next step is a major surgery to remove the lymph nodes on the tongue and the neck, and then she has to learn to speak and eat again.

"I'm 39 and I'm shocked," she told BBC News.

As part of an international study on a new approach to treatment of cancer, experts at the London Cancer Institute, Laura is one of more than 350 patients, as the immunotherapy drug Pembrolizumab before and after the surgery lays the foundation for the body’s defense before and after the surgery.

Professor Kevin Harrington, who led the UK trial, explained: “We give the immune system the opportunity to appreciate the tumor to produce anti-tumor immunity, and then after the tumor is cleared, we continue to extend that immune response by continuously providing medications for up to one year.”

Similar numbers of patients diagnosed with similar cancer received the usual care. They all have advanced head and neck cancer in an area that is not spread to the rest of the body.

The new approach shows positive results. Its time averages the patient's length does not exceed 2.5 years, to 5 years.

Three years later, patients who were given pembrolizumab had a 10% reduction in cancer risk.

Six years later, Laura works full-time and says she is “in a good place and doing a great job”.

“For me, it’s amazing because I’m here to be able to talk to you.

Laura said, “I didn’t expect to go so far.”

“My prognosis is very terrible.”

She snatched the muscles from her left arm and put them in her mouth to fill the gaps left by her tongue. It was a difficult journey.

“Just having this amazing immunotherapy has brought me back to life.”

The key to the outcome is to provide patients with medication before the surgery, which trains the body to capture and kill cancer, the researchers say.

Professor Harrington said that for these patients, immunotherapy “can change the world.”

"This greatly reduces the chances of cancer spreading in the body, which is very difficult," he said.

About 12,800 new cases of head and neck cancer are diagnosed each year in the UK.

Professor Harrington said this approach is “extremely good” for some patients, but it is very exciting to see the treatment that benefits all patients. He added that it should be available on the NHS now.

The results of the study are presented at the annual meeting of the American Society of Clinical Oncology (ASCO).

The trial, called Keynote, involves 192 hospitals in 24 countries, is led by the Washington University School of Medicine in St. Louis and funded by the pharmaceutical company MSD.