Cutting edge cancer treatments which are currently held back as a last resort for patients with no other options could mean people “live years longer” when used as a first choice, experts have said.

Immunotherapies, which reprogramme the immune system to identify and attack tumours, are a promising, but experimental group of treatments usually given after aggressive chemotherapy has failed.

Results from a pair of clinical trials in patients with advanced, treatment resistant cancers found immunotherapy increased survival, with fewer side-effects, when used immediately.

Experts said this shows more needs to be done to make these experimental treatments available to patients when they can provide the most benefit, rather than holding off because of risks or costs.

Both sets of findings were reported at the European Society for Medical Oncology Congress in Berlin.

The first of the trials, led by the Institute of Cancer Research and Royal Marsden NHS Foundation Trust, looked at the immunotherapy drug pembrolizumab in nearly 900 patients with advanced head and neck cancers. The disease had returned to them after treatment or spread throughout the body.

But the immunotherapy drug increased life expectancy by 40 per cent when compared to radical chemotherapy.

Among patients where the drug worked best, median life expectancy after diagnosis was 15 months, compared to 11 months for those given the usual cocktail of chemotherapy and targeted cancer drugs.

Only 17 per cent of patients experienced serious side-effects, compared to 69 per cent on extreme chemotherapy.

The downside of immunotherapies is that not every patient will respond, but modern genetic testing methods can allow doctors to identify which tumours are likely to be vulnerable to certain drugs.

In pembrolizumab’s case, it only worked in around 23 per cent of patients, compared to 36 per cent given chemotherapy.

It was most effective in those whose tumours have particular markers for the immune system to target.

In cases where the drug worked best median cases the results were “unbelievable”, the ICR researchers said.

“We couldn’t believe it when we saw the results,” said Professor Kevin Harrington, who led the study. “None of us expected pembrolizumab on its own to work so well in some of these patients – and it raises the prospect that we could spare some people chemotherapy altogether.”

He added that it could have major implications for these patients, and said: “The trial is still ongoing, but we expect some patients to go on to live for years longer than they would have done had they received standard chemotherapy.”

Another study presented at the conference on Monday looked at immunotherapy treatment in colorectal cancer which had spread.

In around 4 per cent of colorectal cancer patients, the tumour carries a mutation which affects DNA repair and these patients typically survive between 14-19 months after survival, compared to up to 25 months for other types.

The early stage trial, led by University of Southern California researchers, found that 84 per cent of patients saw at least some shrinkage of their tumours when given the immunotherapy drug nivolumab instead of chemotherapy.

After 12 months 77 per cent were alive with no progression in their tumours.

Professor Paul Workman, chief executive of the Institute of Cancer Research said the findings show immunotherapy’s potential as a “smarter, kinder and more effective first-line treatment”.

“We now need to do two things to ensure more patients can benefit from immunotherapy – develop ways of getting these drugs to work in a higher proportion of patients, and come to an agreement over the cost of these drugs to make them more affordable for the NHS.”