Very good point, UM.
What GFunk says is true. The re-treatment rate isn't because it is less effective, at least based on the major studies findings. There was no change in pain relief or narcotic usage. It's just when you give 8 Gy in 1, it's easy to give one more fraction without worrying that they will get sick. After 30 Gy in 10, most of us feel they've reached tolerance.
As far as cost, 30 Gy in 10 fx leads to one extra OTV and 9 additional treatments. Even it was true that 16% actually needed retreatment vs 8% in single fraction arm, if you had 100 patients and 50 got 30 Gy in 10 and 50 got 8 Gy in 1, 4 of the 30 Gy patients would get additional RT and 8 of the single fraction would need retreat (let's guess each retreat was 5 fractions). I never re-sim for a re-treatment bone met - it's just at follow-up, if they hurt, use same iso and same plan. That's my own bias, though.
30 Gy group = 520 total fractions, 104 OTV visits
8 Gy group = 90 total fractions, 58 OTV visits
If you consider that the reimbursement for consult, sim, devices, etc. are all the same between groups, there is still a substantial difference in cost. I don't think we need a study to show this
At least how we are paid, the majority of the reimbursement is for treatment delivery and OTV. If it is case based like Kaiser, then it certainly wouldn't cost more, you could do 40 Gy in 20 fx if you want, but you'd just be using more resources without proven benefit and your staff has to treat many more total fractions.
However, I have a bias against 8 Gy/1 fx, it doesn't seem to work for me. So, I use 20 Gy in 5. I don't think "retreatment" rate is higher, but let's say it is just as high as 8 Gy in 1. Still 520 fx vs 290 fx. 108 OTV vs 58. I am certain there are some cost savings.
I don't think 30 Gy in 10 is wrong. It's a community standard. Just seems too long for me, but that's my bias.
S