There’s no industry money behind studying volumes. Or radiation really.
...
Doesn’t mean pharma is sinister mind you, but no one is making money off if we perfect head and neck or prostate volumes and improve patient survival. But if we add immunotherapy to head and neck radiation? Some one makes a lot of money off that.
I basically agree with what you said, however:
1. There's also no money behing alot of fractionation trials we have carried out in the past in head&neck, lung, prostate.
One exception here would probably be CHHIPP for prostate, since the UK decided to fund this trial by doing the math. They calculated that if they can establish 60/3 as s.o.c., they can refer from buying dozens of new linacs in the coming years, since it would free up capacity. But no pharma industry ever sponsored fractionation trials or combined modality treatment with established drugs (like cisplatin for H&N cancer).
2. You are not going to increase survival by changing volumes, I agree to that. It's going to take thousands and thousands of patients to see differences there. But you will certainly spare patients from toxicity and side effects.
Here's an interesting example on how missing evidence is leading to potential overtreatment.
cT2b cN1 (?) SCC of the cervix
The CT showed one potentially suspicious lymph node in the pelvis. Not really enlarged and the PET-CT showed no avid nodes.
The gynecologists opted for primary RCT but wanted to rule out the suspicious node, so they performed a laparoscopic lymphadenectomy. More than 30 nodes removed, all negative.
So what now? This lady is getting external beam RT folllowed by brachytherapy + cisplatin based concurrent chemotherapy.
I am going to treat the pelvic lymphatics with an elective 45/1.8, but do I really need to do that?
What is the isolated nodal recurrence rate if I opted not to treat them at all? Or if I opted only to treat a "small pelvis"? Or if I de-escalated the dose to 36/1.8 like we do in anal SCC?
Noone knows...
We do have evidence from the postoperative situation telling us that in pN0 and not high-GOG scores (when you deliver EBRT because of a large primary) you can resort to only a small-pelvis-RT when you administer adjuvant RT but there are not data for patients who have had upfront lymphadenectomy, came back negative and are scheduled to undergo primary RT.
Why? Because we have been busy studying induction chemotherapy priot to concurrent RCT, celecoxib as a radiosensitizer, consolidation chemotherapy...