By Jane Elliott
BB News health reporter
Decompression chambers, used to treat deep-sea divers with the bends, could hold the key to relieving a painful side effect of breast cancer.
Shirley Fenton had a badly swollen arm
Experts believe lymphoedema - severe swelling in the arm following surgery andradiotherapy - could be alleviated by breathing in pure oxygen.
A trial funded by Cancer Research UK is now looking for 63 women to test their theory.
Previous trials have already produced promising results.
Five years ago Shirley Fenton, 66, from Buckfastleigh, in Devon, took part in the pilot trial, led by the Royal Marsden Hospital and The Institute of Cancer Research.
She said: "The swelling in my arm has reduced by 10% and the arm has softened quite a lot.
"Before there was no give in it. Now there is no difference to the other side.
"I had swollen fingers that I used to call my sausage fingers, but now I can get my rings on."
Shirley first had breast cancer when she was a young mother of 34.
She had a lumpectomy and radiotherapy, but her lymph nodes were not removed.
Seventeen years later she had another unrelated breast cancer. Again she had a lumpectomy and radiotherapy, but this time surgeons also removed her lymph nodes.
A few years later she started to suffer from a terrible swelling in her arm.
"I did not know what was happening. My arm started to swell up. But I did not let it stop me doing anything and I would still play golf with this enormous arm."
Because Shirley and her contemporaries were the first wave to have their lymph nodes removed, there were few support systems in place - and cancer experts were not as aware as they are today about the symptoms and side effects.
When she was first diagnosed with lymphoedema she was simply given a sleeve, like a stocking for varicose veins, to reduce her swelling.
Later she was told about massage that could help drain the excess fluid.
But she said that because she had the condition for so long, many regarded her as someone whose condition could merely be maintained rather than improved.
When she heard about the six-week trial in the hyperbaric unit, which helps treat divers suffering from the bends, she agreed to take part.
"We were breathing pure oxygen.
Patients will get 90 minutes of HBO for six weeks.
"And then after 90 minutes we would start to decompress. It was like being in an aeroplane, because your ears pop.
"It was an experience I would not have missed for anything. I found it very enlightening."
The treatment, called hyperbaric oxygen therapy (HBO), will be available in Hull, Plymouth, Gosport and Leytonstone.
Professor John Yarnold, a consultant at the Royal Marsden Hospital, is leading the trial.
He said he hoped to show that HBO treatment could permanently reduce swelling.
"Patients cured of breast cancer by treatments that include radiotherapy to the armpit may be left with a life-long legacy of arm swelling.
"This is thought to be due to narrowing of lymphatic vessels that drain tissue fluid out of the arm, rather in the same way that veins drain blood.
"Narrowing of these channels is caused by scarring (fibrosis) stimulated by the radiotherapy. A very similar syndrome can develop after surgery to the armpit.
"For many decades, this complication has been assumed to be inevitably progressive and irreversible, but our recent research suggests that the condition might be improved by high-pressure oxygen therapy.
"Our current clinical trial aims to test the findings of an earlier pilot study, which reported worthwhile improvements in a proportion of patients who had had radiotherapy up to 30 years ago."
He added: " If the present trial confirms our earlier findings, this will certainly change the way we think about lymphoedema as well as, hopefully, changing the lives of patients living with this condition.
"As part of the trial, we are keen to investigate possible mechanisms by which high-pressure oxygen might improve lymphoedema.
"One of the ideas we are looking into is that high-pressure oxygen may stimulate the growth of new lymphatic channels as well as lead to a reduction in scar tissues surrounding existing lymphatic channels in the armpit."
Two thirds of volunteers recruited to the trial will receive 90 minutes of HBO therapy, five days a week for six weeks.
They will wear a large transparent dome over their heads that supplies pure oxygen through tubes and during this time they will be able to read or talk normally.
The remaining third of volunteers will receive standard care for lymphoedema including bandaging, exercise and massage.
Professor Robert Souhami, at Cancer Research UK, said: "Current therapies for lymphoedema aim to control the symptoms rather than treating the cause.
"There are encouraging signs that hyperbaric oxygen therapy might be an effective treatment and this trial will provide stronger evidence."
Women wishing to check if they are eligible for the study should contact Mrs Lone Gothard, Research Coordinator on 020 8661 3460 or visit the cancer trials database on Cancer Research UK's patient information website.