Taking part in a clinical trial for a new cancer drug is not something to be done lightly.
Often the patients involved are at an advanced stage of their illness, and have already been through long and debilitating bouts of treatment. In some cases, the time left to them is short.
So why spend it returning time and again to hospital to be given drugs whose properties aren't yet fully understood - they're on trial after all - and potentially highly toxic?
Kimberly Lewis is perfectly placed to comment. She's just 36-years-old, was diagnosed with Hodgkins Lymphoma in her 20s, and has taken part in a number of trials since then.
She is in little doubt that otherwise she'd be dead by now.
"To me the trials are an opportunity, not just for myself, but to learn and to progress," she said.
"I am so grateful for all the treatments that I have had and all the opportunities I've had to get well and to stay well that it seems like a very small payment to say, yeah, you can have the data and in exchange this might help me or cure me or whatever."
Three years ago she was told the doctors had run out of conventional treatments and were basically in fire-fighting mode.
She has since signed up for two more trials. Neither of them worked out for her long term, but she says they kept her alive long enough for her to start taking a brand new drug that is not just keeping her cancer in check, but actually shrinking it.
Having lived with the disease for so long, however, she remains pragmatic.
"I won't lie - there's always that wild hope that this is it, the magic bullet that's going to fix everything," she said.
"But I'm 8.5 years in now and so while that wild hope is there, there is the realistic notion that if it does something, fantastic - and if it doesn't do anything - that's okay too because it teaches the doctors that perhaps this isn't the right way."
This belief in the importance of making a contribution is something Kimberly, and many of the other patients I met, clearly feels very deeply about. I had been told she was too ill to speak to me, but such was her determination to express her support for the trials process she had the staff call me back in.
As she talks her conviction is sincerely moving.
"I always have a burning hope on some level that I'm being helpful, that I've managed somehow to turn a key in a lock, on any level, and it might be something I never know about - and that's okay. But you kind of hope that in some way, there is a purpose."
Caroline Shaw, chief executive of The Christie, said the hospital is extremely proud to house the world's largest early phase trials unit.
"Thanks to the commitment of our scientists and patients who opt to take part in these trials, we have made great advances in cancer research during our 100-year history and hope to continue developing more treatments to save more lives," she said.
"Almost everyone knows someone that has been affected by cancer, so it is vital that clinical trials continue to grow to further improve cancer treatments for all patients around the world. We are working towards a future without cancer and early phase trials are an important contribution to this objective."
Professor John Radford, consultant at The Christie, said the hospital had been at the forefront of cancer research for more than a century.
"Our commitment to clinical trials has led to many advances in cancer research. The life-saving breast cancer drug Tamoxifen, which was first trialled at The Christie more than 40 years ago, is just one of them.
"Although we have made great progress in clinical research, with cancer survival rates improving over recent decades, we still have a way to go.
"But with world-leading experts, strong partnerships with scientists, and our patients' continuing support, we will make further advances and save more lives."
Part one of Cancer Trials - Behind The Scenes At The Christie will be broadcast on Radio 5 live on Sunday 7th August from 8.00pm. The second part follows two weeks later on Sunday 21st August at 8.00pm.