When a child is diagnosed with cancer, it is every parent's worst nightmare.
Ian Stevens has had to be strong
"I can't explain the feeling, you've got to go through it," says Ian Stevens, from Leeds.
"It just rips the heart out of you, so hard. The only way you can feel what it is like is to be touched by it."
Ian's daughter Nicole has just celebrated her 10th birthday on the wards of St James's Hospital.
She was diagnosed with leukaemia last year and was in remission after one course of chemotherapy.
But last month Nicole and her family were told the news they feared most.
The disease had returned. Nicole is now undergoing another course of chemotherapy, before a bone marrow transplant later in the year.
The family agreed to be filmed for BBC News' cancer week, because they wanted to show how brave Nicole was being in the face of it all.
"I get fed up sometimes," she says. "I didn't know what it was at first, but when they told me it was cancer and that my hair would fall out I thought it was really, really, really hard."
Thankfully, childhood cancers are extremely rare. The disease affects approximately one in 650 children, and treatment is improving all the time.
Nowadays around 75% of children survive the disease, up from just 30% 30 years ago.
It is not just children who are affected when the disease is diagnosed.
Family life is turned on its head and many families struggle to cope.
Matthew Parsons, 11, is recovering from Hodgkin's Lymphoma at home in Bradford.
Matthew's mum Gillian had to give up work when her son was diagnosed and the family struggles financially.
"It is difficult for the whole family," she said, "but thankfully we've had some brilliant help. And you get through it because you just have to."
There is little doctors can do for David Hood
Matthew's family are supported by CLIC Sargent, Britain's leading children's cancer charity.
Volunteers support the family by helping out with day to day chores.
They even redecorated Matthew's bedroom so he would have a suitable room in which to recuperate.
There are particular issues when treating older children.
Many teenagers end up being looked after either on adult wards or children's wards - and neither are really suitable.
Chance to socialise
The Teenage Cancer Trust funds specialist wards where teenagers can be treated in their own environment, with video games, computers and the chance to socialise with others the same age.
One of these wards is at St James's hospital in Leeds and its lead nurse is Sue Morgan, a Macmillan nurse specialising in the care of young people.
"It's an absolute privilege to work with these young people," says Sue. "It can be the hardest place in the world to work, but it can also be the best place in the world to work."
For some, the news is bad. 18-year-old David Hood has just been told that his bone tumour has spread to the rest of his body - and there is little that doctors will be able to do to save his life.
Yet David has accepted this news with dignity and courage - and returned to Beverley in Humberside to spend his last months at home with his family.
"Meeting someone like David is a heartbreaking privilege," says Sue Morgan.
"The young people on this ward can be unbelievably strong."
At St James's hospital, teenagers and young adults are encouraged to help out with Jimmyteens TV, a video project posting video diaries and short documentaries on the internet.
Millie has been given the all clear
The project provides a vast resource of films in which young cancer patients share their experiences.
One of those to benefit was Millie Smith. She was diagnosed with Hodgkin's Lymphoma last year and spent many months receiving chemotherapy on the teenage ward at St James's.
Now she has been given the all clear, and has just taken her A levels.
"My message to anyone going through this is to take every day as it comes," says Millie.
"Have your family and friends there with you because they help a lot, and you'll get through it. I'm much stronger from the experience."