Boron neutron capture therapy for brain tumours

Boron neutron capture therapy (BNCT) is an experimental way of giving radiotherapy that has been used in trials with glioblastoma multiforme (grade 4 glioma) and some other types of cancer. There are concerns that the treatment causes severe side effects, so trials continue in Europe and the USA. 

BNCT is really a combination of treatment with boron and low energy neutrons. Radiotherapy using neutrons can get rid of glioblastoma cells. Unfortunately, at the dose needed to do this, too much damage is caused to healthy brain tissue.

In BNCT, boron is injected into the bloodstream and collects in tumour cells. The next stage of the treatment is external radiotherapy with low energy neutrons. The boron molecules give off radiation within the brain tumour cells when the external neutron radiation hits them. This enhances the radiation dose by about 2 or 3 times. So, a lower dose of neutron radiotherapy can be given. This makes it less likely that the neutrons will cause damage. 

Unfortunately, there have been reports of damage being caused by the boron in the brain. This was an unexpected complication and more research needs to be done to confirm or deny this. There are no trials for patients going on in the UK at the moment. BNCT research is going on here, but it is still at the pre clinical (laboratory) stage. Hopefully, this will lead to an early phase clinical trial in the near future. 

There is an early phase trial in the US for people with newly diagnosed glioblastoma multiforme. The trial is testing BNCT with a chemotherapy drug called temozolamide. Early phase trials look at side effects, doses and whether there seems to be a response for a particular cancer. It is only in later phase 3 trials that we can see if a new treatment works any better than an existing treatment. So it will be some years before we have any long term results for BNCT.