A record-breaking 4,855 people waited for hours in the rain to get tested to see if they were a match to help save a 5-year-old boy fighting a rare cancer.

The potential donors volunteered to help brave Oscar Saxelby-Lee following a desperate plea from his parents.

The youngster is in a race against time to find a life-saving stem cell donor after he was diagnosed.

His parents became concerned when severe bruising turned out to be T-cell acute lymphoblastic leukemia (T-ALL).

Doctors say he now has just three months to find a stem-cell match that could save his life.

Over 4,800 donors lined up to get tested after Pitmaston Primary School in the United Kingdom opened their doors for a donor search over the weekend.

His teacher Sarah Keating said: “I’ve been teaching for 20 years and I’ve never had a child go through something like this.”

“You hear about children getting cancer and you think, ‘That’s dreadful,’ then you move on. In this case, we haven’t moved on, we will fight this.”

Oscar’s teaching assistant, Laura Senter, 22, said his diagnosis came as a shock to their class.

She added: “I couldn’t believe it. I saw him before Christmas and he was his usual happy-go-lucky self. It’s a nightmare for this to happen. You can’t really do anything about it, it’s heart-breaking.”

“If a child falls over and cuts their knee, you can put a plaster on it. With something like this, you can’t just fix it. That’s why we have gone into ‘action mode’ to try and find a donor. I visited Oscar in hospital last month when it was his birthday.”

“All the parents bought gifts for him.”

“Because of all the chemo, he was very swollen, but you could tell he was very much still him inside. When we came out, we knew we needed to do everything we could to support him.”

DKMS, the charity that tests the swabs, said its record for the highest number of people to take part in a registration event is 2,200 people.

Volunteers sat at tables and chairs in two of the school’s halls over the weekend, handing out swabs and completing donor registration forms.

Oscar was diagnosed with the aggressive form of leukemia after the T-ALL diagnosis Dec. 28.

His desperate parents, Olivia Saxelby and Jamie Lee, of Worcester, UK, launched an appeal to find a match after his diagnosis.

They aimed to get as many people as possible to sign up to a blood stem cell donor registry as part of a campaign called “Hand in Hand for Oscar.”

Saxelby, 23, said: “We felt like we could not see light at the end of the tunnel, but when looking at Oscar’s cheeky smile, bravery and determination, we managed to pull our strength together again.”

“From that moment of fear and confusion, we as a family became stronger than ever. Oscar reminded us how to fight again and just how courageous he is. Not once has he shown weakness, nor has he ceased to amaze us throughout the most difficult times, and that to us is a true warrior.”

“Oscar is a fun, loving, energetic 5-year-old boy who deserves to live to the full alongside the other troopers fighting such horrific diseases.”

“Not only does he need to enjoy a normal life a child should live, he now needs someone else to save him.”