By Jane Elliott
Health reporter, BBC News
A doctor drawing a syringe of bevacizumab (Avastin),
Wendy Martin had to do a lot of soul-searching when she was offered a place on a drugs trial.
On the one hand Wendy, who had bowel cancer, had the chance of extra treatment, alongside her routine six months of chemotherapy. But on the other, she faced a year of potentially serious side effects.
"I did a lot of soul-searching, got all the information and sat the family down and we all discussed it," she said.
"My husband was concerned that despite all this heartache and soul-searching I would go on the trial and I might be one of the 50% that did not get to take anything extra.
"We looked at the pros and cons and decided that it was worth trying and that it might ultimately help someone.
"I would want people to go through drugs trials if I thought it would help people like me, and so I thought I should do the same.
Wendy was warned that the cancer drug Avastin (bevacizumab), which works by blocking the formation of new blood vessels, could have serious side effects.
And she was warned that she might feel so debilitated during her 12 months on it that she might need a year off work.
"The side effects were tremendous so the whole family had to rally around to ensure everything got done," she said.
"I had fatigue, nausea, diarrhoea and mouth ulcers but the thing they were most worried about was the hand foot syndrome.
"As the drug was strangulating the blood supply it could affect your feet and hands. So they monitor them very closely to see you have not got any problems and I was very lucky.
"But by the end of the year I had so much of the drug in my system that I started to notice it and by the end my feet had got to sore I could not really walk."
Although Wendy, 52, has now stopped taking the drug she still does not know the results of the trial which has another few years to run.
Clinical trials, such as the one Wendy entered, test potential treatments in humans to see if they should be approved for wider use in the general population.
Any new treatment must be extensively tested to check that it works, is safe and doesn't have unacceptable side effects.
A new treatment may not be better and could even be worse than existing treatment, for example.
Wendy took part in a trial
Most often the treatment is a drug, but it could be a medical device, a surgical or physical procedure, a therapy or an intervention such as health promotion.
Each year thousands of people take part in trials, and the DIPEx Health Experiences Research Group at the University of Oxford recently launched a new initiative to try to help people with deciding whether to participate.
It spoke to 40 people, including Wendy, who explain why they took part - or chose not to take part - in a clinical trial, what information they needed and what it was like for them.
Sir Iain Chalmers, editor of the James Lind Library - created to help people understand fair tests of treatments in health care - said people should consider whether their trial answered three important issues before agreeing to participate.
"They should decide whether the trial is answering an important question then see if the protocol for the trial has been registered in public, so everyone can see what is going on and what is intended.
"They should also have a written undertaking that the trial - whatever its results - will be reported when it is finished and that those taking part wishing for copies of the trial will be accommodated."