Is spending on proton beam therapy for cancer going too far, too fast?

You might think that this week’s study of 12 000 patient records showing that men with prostate cancer treated with expensive proton beam therapy had more complications than patients given conventional radiotherapy would dent some people’s faith in the newer treatment.1 No clear evidence of better effectiveness exists, and it now appears that the treatment may have a downside.

But the spread of proton beam therapy for cancer has such momentum it now seems unstoppable. Millions of dollars have been invested in building the particle accelerators necessary to deliver it.

Globally, 39 facilities are in use. The US has 10 proton beam centres, and 19 more are being built. More than $370m (£230m; €277m) are being spent on a project to bring accelerators to centres in Minnesota and Arizona. And the UK’s health secretary Andrew Lansley announced in December that £150m would be put into delivering such treatment in the NHS.2

Some people have recognised the rashness of the dash to …