Researchers from Massachusetts General Hospital and Harvard Medical School in Boston, MA, have performed a detailed evaluation of the second cancer risks for paediatric patients with brain or head-and-neck tumours (Phys. Med. Biol. 59 2883). They compared four treatment modalities: passive scattered and pencil-beam scanned proton therapy (PPT and PBS), intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT).