Pho sho.

Headline: The dosimetric superiority of protons finally translates to clinical gain for the first time. Perhaps the most interesting part of this phase 2 study comparing protons to IMRT for esophageal cancer (n=105) is the complex assessment of treatment toxicity. We’re used to phase 2 trials choosing either an overall toxicity grade outcome or toxicity for a single domain, such as pneumonitis or cardiac toxicity. Because any comparison of protons and photons is gonna come down to toxicity, this trial uses a complex toxicity measure called the treatment toxicity burden (TTB), a measure of the sum of all graded toxicities within a year of treatment. In other words, the TTB approach makes the trial more sensitive to picking up potential discrepancies in global toxicity. Alas, TTB was over twice as high, and post-op complications 7x as high, with IMRT than with protons.

TBL: Protons for the treatment of esophageal cancer to reduce toxicity has clinical momentum as it enters phase 3 testing. | Lin, ASTRO 2019