Is There More to Radiotherapy than Hitting the Target?

One in two cancer patients are routinely treated with radiotherapy, using a linear accelerator to deliver the radiation dose. Conventionally, a treatment meets guidelines when the tumour is uniformly irradiated, but the surrounding normal tissue is avoided [1]. However, our recent study upsets this radiation therapy “dogma” [2]. We have shown that a radiation field with many high dose gradients may have an advantage over a uniform field [2], because it is more lethal to cancer cells than to normal cells. We attribute this effect predominantly to the production, diffusion and response to radiation induced bystander signals, which is consistent with previous reports of up to 60% of cell death following irradiation being attributed to bystander effects [3,4].