Proton beam therapy offers potential to treat childhood brain cancer with fewer severe side effects than conventional radiotherapy, according to US researchers.
Proton beam therapy to treat the childhood brain cancer medulloblastoma appears to be as safe as conventional radiotherapy with similar survival rates, according to research published in The Lancet Oncology journal.
“Proton radiotherapy resulted in acceptable toxicity and had similar survival outcomes”
Importantly, the findings suggest that proton radiotherapy may not be as toxic to the rest of a child’s body as conventional radiotherapy.
Medulloblastoma is the most common malignant brain cancer in children, and develops at the rear and base of the brain, near the bottom of the skull. They are rapidly growing tumours that, unlike most brain tumours, spread through the cerebrospinal fluid to different locations along the surface of the brain and spinal cord.
Conventional treatment usually involves surgery to remove the tumour, photon radiotherapy and chemotherapy.
However, patients are often left with significant side effects including hearing loss, effects on cognition, hormone function as well as toxic effects on the heart, lungs, thyroid, vertebra and reproductive organs.
Compared with traditional radiotherapy, proton beam therapy is highly targeted and is used to treat hard-to-reach cancers, with a lower risk of damaging the surrounding tissue and causing side effects.
Two UK centres for proton beam therapy are currently being planned – in Manchester and London – which are due to open in 2018.
In the latest study, 59 patients aged three to 21 were followed-up for around seven years. Most had the tumour partially or completely removed through surgery and all received chemotherapy as well as proton beam therapy.
At three years after treatment, 12% of patients had serious hearing loss, rising to 16% at five years.
Study backs proton beam therapy for child cancers
Source: Dr David R Grosshans
Patients also displayed problems with processing speed and verbal comprehension, but perceptual reasoning and working memory were not significantly affected.
At five years, 55% had problems with the neuroendocrine system that regulates hormones – with growth hormone being the most commonly affected.
However, the study reported no cardiac, pulmonary, or gastrointestinal toxic effects, which are common in patients treated with photon radiotherapy.
At three years after treatment, progression-free survival was 83%. At five years, progression-free survival was 80%.
The study authors said: “Our findings suggest that proton radiotherapy seems to result in an acceptable degree of toxicity and had similar survival outcomes to those achieved with photon-based radiotherapy.
“Although there remain some effects of treatment on hearing, endocrine, and neurocognitive outcomes – particularly in younger patients – other late effects common in photon-treated patients, such as cardiac, pulmonary, and gastrointestinal toxic effects, were absent,” said the researchers from Massachusetts General Hospital.
They added: “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.”