Statistics from the charity show everyday 10 children will receive a cancer diagnosis.
Out of the 10 diagnosed two will not survive, but of the eight that do, over half will face long-term and life-limiting side effects.
Chief executive Gavin Maggs said: “We have to share stories like Leah’s which can help young people through their cancer journeys.
“We know that children can be left suffering with their mental health after cancer but it’s important that they know they still have a life to lead.”
Leah, who in December celebrated Aria’s first birthday, believes young people with cancer need to “talk more” about the disease.
“I still face challenges with my pain, cancer changes a person, you may think this is not the life I imagined growing up but it is a life and we’ve got to be so thankful.
“If someone had told me I’d be here with a one-year-old, I would have said that was impossible. Yet here I am, in the best place I’ve ever been.
“Things really can get better – not just in small ways, but in ways you never imagined.”