My hope is that they are very open with the data. It won't "prove" anything but it would put more trust in the process.
This is the key. Let us see the publication. There should be extensive and transparent appendices with access to raw toxicity data.
This is what the trialists who ran FAST and FAST-FORWARD breast trials did. They did an excellent job.
Now...toxicity is exceptionally hard to measure in a meaningfully comparative and reproducible way (this was demonstrated in the above trials). Low level toxicity is basically subjective and severe toxicity is rare.
Low level toxicity in a non-blinded trial is just going to be lost entirely as a meaningfully measurable thing.
As severe toxicity is rare, it is not subject to the type of statistical tools we usually use to demonstrate "equivalence". (3 airplane crashes is not the same as 1, 5 ORN of the jaw is not the same as 0). 5 fraction breast XRT appears equivalent in terms of late toxicity to 15 fraction breast, but the rare marked toxicity is more common in the 5 fraction arms per their own data. We need to see the raw data.
I suspect that the toxicity profiles of protons and photons are different...but in a complicated way. Steeper dose fall-off and less low dose bath help in some domains and localized dosimetric uncertainty and the marked sensitivity of proton dosimetry to biological environment will hurt in others. (e.g. lower volume mucositis acutely but a higher risk of ORN long term). By the time you have to create at TTB tool to assess relative toxicity, you are acknowledging that one tool is not necessarily preferable to another.
When that it is case...they should be valued the same by payors.
Admittedly, as a community doc, my bias against protons is so strong at this point that I would need really remarkable data to see the differential value.
Where did my bias come from?
1. Seeing in real time how academic leaders came to adopt a favorable position on proton therapy in the late 2000s/early 2010s. IMO, it was not due to a true belief in the science or the differential value of the intervention...it was due to prestige and dollar signs. (Although Jim Cox was a true believer).
2. Terribly lagging science and false narratives.
The specious RBE of 1.1! the discordant cell line data; the clear dosimetric uncertainties that were never emphasized during the hype-period of protons; the complete lack of nuanced understanding of proton dosimetry by most proton docs.
3. Knowing docs who used protons and moved away. Their assessment of the value of the intervention. Their descriptions of "toxicity rounds" regarding proton patients. Their description of how much of a hassle it is and how often photons end up being incorporated into the plans in real life.
4. Knowing a nurse in a prestigious long term care facility for children.
I mean, what do you tell a kid with medulloblastoma? Protons are likely to reduce late cognitive side effects, but there is a greater risk of locked-in syndrome?
5. The direct to patient marketing in the face of all of the above.
FWIW, I have no problem with kids getting protons in many circumstances (although certainly not all).