By Jane Elliott
Health reporter, BBC News
Lisa Hudson's dream was to join the Metropolitan Police.
Lisa has completely recovered
But in her final year at university she was diagnosed with a pre-leukaemic condition, myelodysplasia, and told that without a bone marrow transplant she probably had just five years to live.
Lisa put her career plans on hold after having her transplant and gruelling treatment. Eventually, she got a job working in a high street store.
"I had to have a year off work after the transplant," she said.
"I spent the first three months in hospital and then the next six months in isolation to make sure I did not get any infections.
"Even when I started to slowly get better it was really difficult because people did not know what to say to me. All my hair fell out and the steroids made my face balloon.
"I felt pretty horrendous. It was a really hard time, much harder than going through the transplant itself."
Lisa's hopes of joining the police seemed remote with her health so fragile.
"It was absolutely awful. I had to put my life on hold," she said.
Gradually she improved, however, and just over three years ago, after getting the all clear from her doctors, Lisa finally applied to join the police.
Lisa has run in the London marathon
Today she is fully fit and a cycle-riding police officer, based with the safer neighbourhoods team, in Wanstead, London, and loves her job.
"When I left university I was not well enough to do this job," said Lisa, 28.
"I knew it was what I wanted to do, but I knew I would not fulfil the medical criteria.
"So when I was better I got my doctor from the Royal Free Hospital, in London, to write me a letter for my medical which I took along with me.
"I had spoken to the police to check what I would need and they said if I could take a letter with me saying that I was fit enough to work for 30 years, then the doctors should be happy with that.
"They don't really want you to get into the job and then go off sick and then end up having to pay you sick pay."
Lisa said her colleagues are surprised when they find out about her medical history - but is positive there is nothing other Pcs can do that she cannot.
"I am out cycling most of the day, doing everything everybody else does basically," she said.
"My colleagues are very supportive, but quite surprised that I have managed to put it all behind me and get on with my life.
"I have been in the service three to four years now. The police have been brilliant."
Lisa was successful at the transplant games
Lisa has even competed in the British and world transplant games, winning golds at both for badminton.
She knows however, that it could have been a very different story were it not for the Anthony Nolan Register, which collects the details of potential bone marrow matches.
Lisa was lucky the register found her an immediate match and although her condition was not immediately life threatening, she was advised to get a speedy transplant rather than wait until her condition developed into full-blown leukaemia.
"My chance of surviving the transplant was far greater if I had it straight away," said Lisa.
"There was the chance that it could turn into leukaemia at any time and if that happens your chances of surviving are slimmer.
"I'd gone to hospital thinking I had something like anaemia - so I was pretty shocked.
"The transplant saved my life. Without it, I wouldn't be in the position I am now. I'm just a normal person now."
John Goldman, professor of haematology at Imperial College, London, said it was important to act as quickly as possible with patients like Lisa.
He said: "It is a very variable disease in prognosis and outlook. The sooner she had the transplant the better."
Professor Goldman said the register was a "crucial tool" in the fight against leukaemia allowing doctors to trawl millions of potential donors worldwide to find a match.
"We immediately go to the voluntary registers of the world to try and find a match," he added.
The Anthony Nolan Trust is calling for more donors to join its bone marrow register.
Dr Steve McEwan, of the Anthony Nolan Trust, said: "Transplants like Lisa's are only possible if there are suitable donors available.
"There are currently 7,000 patients worldwide awaiting life-saving bone marrow transplants. Anyone out there could provide the only suitable tissue-type match for a particular patient.
"If you are that unique match, you are the only person in the world potentially able to save that person's life."