Protons and cons

It’s Asco week in Chicago: the biggest meeting of clinical oncologists in the world. McCormick Place convention centre, the largest in the US, is filled to its 2.6 million square foot capacity with people talking about cancer. And one of the hottest topics being discussed is something called proton therapy, a possible new tool in the anti-cancer arsenal.

But does it actually work? Given that two private proton therapy machines have already been built in the UK, and that two more NHS machines are on their way at a cool £250 million, you’d think we’d know. The sad truth is that, for many cancers, the medical jury is still out as to how helpful these machines actually are.

Proton therapy is a new kind of radiotherapy. Radiotherapy has been successfully used to treat cancer for decades. In essence, it’s a way of using targeted energy to destroy tumours, with standard radiotherapy machines using light particles (photons) as their mode of attack.