Two fractions is probably a bait and switch. When patients come they will be told that they need 45 fractions of protons for their low-risk prostate cancer and it is malpractice to offer anything else.
??? Weird take.
40-45 fraction prostate very much back en vogue in Florida proton centers
Spacer mandatory
Love that experimental arm dose tho...
I think he means to control arm being 73.8 Gy
"Some design elements of this trial may be criticized. First, although the noninferiority margin was prespecified, some may view the margin (7.5% absolute difference or HR < 1.52) as too great. The observed HR of 0.85 (95% CI, 0.64 to 1.14) for DFS and 0.77 (95% CI, 0.51 to 1.17) for biochemical recurrence favors the hypofractionated regimen and should mitigate concerns that it is actually worse than the conventional regimen. Second, some may contend that the prescription dose in the conventional arm was too low, but this dose was specified such that > 98% of the prostate received ≥ 73.8 Gy. Because the protocol allowed ≤ 7% inhomogeneity, portions of the prostate received doses > 76 Gy. A recent analysis of > 12,000 men with low-risk prostate cancer found no evidence that doses > 75.6 Gy improve overall survival.28 Perhaps the most important criticism is that many of these men with low-risk prostate may not need any treatment at all. Active surveillance is an appropriate initial strategy for men with low-risk disease and has increased in use during the last 5 years29; however, a significant proportion of men with low-risk disease still opt for definitive treatment even today, and these results should inform those who elect external beam RT.29"
Rapid accrual and closure ahead of schedule suggests that someone (many people) were OK with the trial design and doses used. Remember this was written more than two decades ago when active surveillance was infrequently used.
I disagree with the premise that two variables were changed. Biologic effective dose depends on total dose, dose per fraction and (maybe in prostate) time.
Never understood why nsclc got 60-63 back then and sclc got 45. But i digress
My understanding, for SCLC, radiobiologically you get adequate cell kill with a lower dose, so it is more about the number of fractions than total dose. At the same time, time matters, specifically time to 45 Gy, so from a theoretical basis I've always preferred BID. I also am not a huge fan of hypofractionating when doing consolidative thoracic radiation in extensive stage. I think 54 Gy in 36 fractions BID is a bit overkill, but I'm not sure 10 fractions of 3 Gy is really the sweet spot there either. I usually do something in between.
I don’t get why people didn’t just invest in Tesla at the beginning! Also, more people should have predicted Trump winning in 2016. It’s so obvious now.
Time is important but it's a secondary byproduct of choosing small fraction sizes (and repopulation if you didn't subsequently hyperfractionate). The radiobiological rationale is right there on the first page of the 1999 NEJM article:
Exactly. I used to present both, but along the lines of being the doctor and make a recommendation and the same rationale of why I don't spend an hour going over 20 different treatment options for prostate cancer, I now just recommend BID in my plan. If they raise objections or there is a significant logistical problem, then the discussion of daily comes up (or if I can tell it's going to be an issue). 80-90% of the time BID is accepted. It is less satisfying when med onc flat out tells me to do daily. But they are the boss.
Glad ya'll get patients willing to do it.. realistically, it just doesn't happen in rural america when people have to drive long distances or are older, or have limited resources, or the price of gas, or etc etc.
I work 50 miles from Detroit
Yes 100 percent of time
I'd also wonder about the feasibility of doing a sequential boost with a replan after 30. Carve dose out of the esophagus heart and take the reduced volume gross dz only to 60. I'm hesitant to make up stuff, but the concern with going to 60/40 is esophageal toxicity. That way you at least deliver the 45/30 standard of care, and if there really is a benefit of 10 more fractions, you are at least getting some of it this way with hopefully an acceptable toxicity tradeoff until there is a clearer answer. I haven't done this yet, but the concept is appealing. I struggle with esophageal toxicity enough with 30 fractions.
I’ve found with IMRT + GTV only coverage tolerance way better
So you just circle (on the 4D scan) the gross tumor, gross nodes, add a PTV margin and treat all the way through like that? I was trained to add a CTV expansion and include the rest of the nodal station at the levels the CTV expanded to, and I usually do a tad bit of electivsh expansion beyond that. Yes, I could see where toxicity would be a lot better that way.
GTV + CTV (use brush to generate this - 5mm for parenchyma, 0mm for LN in mediastinum and edit out of stuff) + PTV
On this topic, what about the hilum? Remember some epic chart round debates on that one.
Yep... Bid is just tough all around on the staff and patients many of whom have ride issues, use Medicaid transport, unreliable public buses etc, esp when we are talking single Linac places
I won that battle! There were many casualties that day.
It's incredibly stupid post rtog/calgb rct results
