More than £2,000 has been raised by a five-year-old boy who wanted to thank the hospital that treated him for a rare form of cancer.

Little Louis Kayum, from Lewisham, was diagnosed with stage 4 neuroblastoma in May 2015, when he was just three years old.

The cancer develops from nerve cells left behind from a baby’s development in the womb. Its cause is unknown and affects about 100 children each year in the UK.

It is most common in children aged under-five.

Louis was transferred to the Royal Marsden’s Oak Centre for Children and Young People, in Sutton, where he underwent 17 months of treatment following his diagnosis.

His mother, Cat, said: “The Royal Marsden became a home-from-home for our family. He underwent chemotherapy, surgery, a stem-cell transplant, radiotherapy and then immunotherapy.

“The doctors, nurses, therapists, play specialists and support staff were all amazing and we are so thankful for them getting Louis to where he is now. He is now a happy, chatty boy, enjoying life and getting stronger.”

She added: “During last year’s Marsden March, Louis was an inpatient and saw some of the celebrations out of his window. He was having a very hard time as he had just started his immunotherapy treatment.

“This year he got to cut the ribbon at the five-mile start line and was amongst it all, raising money for the children and adults who are still having treatment, and for others who will need this fantastic hospital in the future.”

Louis and his family were among the 5,500 people who took part in the seventh Marsden March on Sunday, March 19.

Each year participants walk either 14 or five miles between the Royal Marsden’s Hospitals in Chelsea and Sutton. Since it began six years ago walkers have raised about £8.2 million for the Royal Marsden Cancer Charity (RMCC).

Money donated to the charity funds cancer research, diagnosis, treatment and care.

Antonia Dalmahoy, director of the RMCC, said: “It’s been amazing to see thousands of inspiring people coming together to raise money for The Royal Marsden. We are so grateful to all our incredible supporters. It’s with your help that we are able to make a real difference for people with cancer.”