A cancer treatment at the centre of an NHS controversy in 2014 causes fewer side effects in children than conventional radiotherapy, according to new research.

The study, published in The Lancet Oncology, suggests proton beam therapy is as effective as other treatments. Researchers looked at 59 patients aged between three and 21 from 2003 to 2009.

All the patients who took part in the study, led by Dr Torunn Yock from the Massachusetts General Hospital in the US, had the most common kind of malignant brain tumor in children, known as medulloblastoma.

After five years, their survival rate was similar to that of patients treated with conventional X-ray radiotherapy, but there were fewer side effects to the heart and lungs, the study found.

The paper said: "Proton radiotherapy resulted in acceptable toxicity and had similar survival outcomes to those noted with conventional radiotherapy, suggesting that the use of the treatment may be an alternative to photon-based treatments."

It uses charged particles instead of X-rays to deliver radiotherapy for cancer patients. The treatment allows high-energy protons to be targeted directly at a tumor, reducing the dose to surrounding tissues and organs. In general, it gives fewer side effects compared with high-energy X-ray treatments.

It can be used to treat spinal cord tumors, sarcomas near the spine or brain, prostate cancer, lung cancer, liver cancer and some children's cancers.

Independent expert Prof Gillies McKenna, who is the head of the department of oncology at the University of Oxford, said the research suggested that the "side effects are indeed dramatically reduced" with proton beam therapy.