Lead researcher on the project, Dr Gareth Veal, senior lecturer at the Northern Institute of Cancer Research at Newcastle University, said: “This could have serious repercussions for the outcome of the child in terms of long-term survival.

“We have now started increasing dose levels so that patients receive a personalised dose that leads to drug exposures that we hope will be beneficial.

“We will be following up these patients to see if it makes a difference to survival rates.

“It’s too early to say if these changes will improve long-term outcome for this type of cancer but I would anticipate that increasing the dose of this drug could lead to an increased chance of survival for many children.”

Carla Johnson, whose son Joe was diagnosed with neuroblastoma when he was three-and-a-half years old, said she welcomed the research. The mother, from Stocksfield, Northumberland, remembered desperately trying to squeeze every drop from Joe’s 13-cis-retinoic acid capsules for the six months he took the drug.

Fortunately the treatment was a success and Joe, now eight, is in remission.

“It was awful because he was too little to swallow them, so I had to heat the capsules up and get all the liquid out of the casing,” she said. “It was very complicated and the pressure was on you as a parent to do it right.

“If I’d had the option to increase his dosage, I absolutely would have done it. Neuroblastoma is such an aggressive cancer, you only really get one chance to treat it so you need to do whatever you can.”

Dr Veal and colleagues studied 70 patients receiving 13-cis-retinoic acid from hospitals around the UK and found that particularly in babies, where doses prescribed are often lower than those received by older children, levels of 13-cis-retinoic acid in the blood were frequently much lower than those thought to be effective.

The study has led to changes in the way that this important drug is dosed in the majority of neuroblastoma patients, with babies now given the same dose as older children and patients who are not able to swallow the 13-cis-retinoic acid capsules also prescribed an increased dose level.