Media playback is unsupported on your device Media caption How does the pancreatic cancer vaccine work?

A trial has begun on a vaccine treating pancreatic cancer, which has the lowest survival rate of all common cancers.

More than 1,000 patients with advanced pancreatic cancer have joined the TeloVac trial at 53 UK hospitals.

Vaccines are usually associated with preventing infections, but this is part of a new approach to try to stimulate the immune system to fight cancer.

The trial involves regular doses of vaccine together with chemotherapy and compares this with chemotherapy alone.

The vaccine contains small sections of a protein, telomerase, which is over-produced by cancer cells. The aim is to stimulate the immune system to recognise the telomerase which sits on the surface of the cancer cells and to target the tumour.

For someone who's never smoked and hardly ever drank, it was a big shock Rhona Longworth, Patient

Professor John Neoptolemos from Royal Liverpool University Hospital, who is helping to co-ordinate the trial, said: "The problem is tumours are clever and are able to turn the immune cells into traitors which help to guard the tumour.

"The vaccine takes away the masking effect of the tumour."

Pancreatic cancer has the worst survival rate of all common cancers. Just three in 100 patients survive the disease for five years or more.

Rhona Longworth, 43, who was diagnosed with the cancer in February, said: "For someone who's never smoked and hardly ever drank, it was a big shock.

"I just hope the vaccine works and I'm one person who goes on to live a happy, healthy life after this."

Joan Roberts, 69, said the vaccine appeared to have few side effects and she is keeping her fingers crossed about the impact on her cancer.

"I'm pleased that it's stable and it hasn't got any bigger. You've got to remain positive," she said.

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The TeloVac trial is being funded by Cancer Research UK. The charity is supporting trials against a range of cancers, using vaccines or antibody treatments to stimulate the immune system.

Cancer Research UK's chief clinician Professor Peter Johnson said: "One of big problems with cancer treatment is you are almost always left with a few malignant cells and it is from those few cells that the cancer can regrow.

"If you can programme the immune system to recognise those cells and get rid of them altogether or keep them in check then you can effectively stop the cancer from growing back lifelong."

The South Korean manufacturer of the vaccine, KAEL-GemVax, is planning a lung cancer trial later this year using the same technology.

Last year the first therapeutic cancer vaccine was licensed in the US as a treatment against prostate cancer.

The Phase III or final stage TeloVac trial should produce results in just over a year which will show whether the vaccine has a positive effect.

Cancer Research UK is keen to stress that the vaccine is not a cure, but if it works, might prolong life.