Tomo better than RapidArc

[scarbrtj]

Clinical Outcomes of Several IMRT Techniques for Patients With Head and Neck Cancer: A Propensity Score–Weighted Analysis

Filed under "How'd I Miss This." You know you wonder about these things. In your mind you think every IMRT/VMAT treatment machine is just a scalpel: a blade is a blade is a blade. Maybe not? I don't know. The study can't answer the question definitively. But still. Pretty interesting result I gotta say.

---

Members don't see this ad.

 

[medgator]

14 centers with different equipment.... seems like quite a difference. Were the newer-trained guys treating at the tomo practices?

 

[BobbyHeenan]

I always liked tomo for head and neck cases. It was abysmal treating SBRT on that thing though. Took forever and that MV CBCT left a lot to be desired.

Just too many variables in this study to say anything definite. Even within my own department back in residency the elective volumes covered, doses, CTV's, margins on head and neck cases could vary drastically.

 

[Palex80]

This is heavily biased.

The problem is that you do not know where the differences resulted from. It is however interesting to note, that °III acute toxicity was greater in the tomotherapy group of patients (62.2%) vs. in the RapidArc group (45.5%) [p=0.034].
Bearing in mind that local control and cancer specific survival were lower in the RapidArc group, one could jump to the conclusion that contouring and planning in the RapidArc group of patients was carried out by physicians and dosimetrists who were trying to lower acute toxicity at the cost of effective tumor treatment.

RapidArc: less side effects & worse tumor control
Tomotherapy: more side effects & better tumor control


Plus one more point:
The French public health system installed tomotherapy at 3 sites, distributed in the country. Of course the tomotherapy machine was installed each at the leading local site.
So when the article states that 166 patients were treated in 14 sites (74 tomotherapy + 92 RapidArc), it's actually 74 tomotherapy-patients at 3 sites and 92 RapidArc patients at 11 sites. All of them treated over a time frame of 2 years, meaning: 12 patients per site per month in the Tomotherapy-grup (or 1 patient/month) versus 4 patients per site per year in the RapidArc group (or roughly 1 patient every 3 months). I guess that if you do something 3 times more often, you may be able to do it better at some point or at least have the chance to learn how to do it better...

So, it's a matter of expertise / patients volume as well.

 

[Burt Radnolds]

I have a hard time putting much stock in that. We routinely struggle to identify differences in outcomes between treatment techniques with larger more rigorously controlled studies. This is a nonrandomized study with the potential for significant confounding factors no matter what statistical wizardy was applied. Yes, I read the whole manuscript. Sure, it's interesting but as they note, what treatment you got was pretty much based on what center you were at. Weaknesses: Non-randomized, 14 French centers with treatment determined by center, small numbers, no mention of HPV/p16 (the single biggest driver of head and neck outcomes).

Apparently there was another earlier paper from this data that examined the dosimetry closer and noted more homogeneous conformal plans with possibly less dose to OARs with Tomo so I can possibly buy the salivary function portion, but I don't want to be accused of cherry picking what I like and don't like arbitrarily, and a large amount of plan quality is dosimetrist dependent. Tomotherapy is pretty cool and more elegant, but may just be easier for a bad dosimetrist to get a good plan. I have personally seen a good dosimetrist plan a better H&N plan on an out of service outdated treatment planning system than a bad dosimetrist on Tomotherapy.

 

[evilbooyaa]

Agree that it's most likely tied to the number of cases treated at each center rather than the treatment modality. I think there's an NCDB study out there stating that higher volume places have better outcomes than lower volume places for H&N cancer.

That being said, this gives you incentive to push for Tomotherapy at your institution if you have any say in the matter. Certainly don't think it's bad medicine to treat H&N on non-Tomotherapy, however.

 

[seper]

Still, it's a well done hypothesis-generating study, and it trumps anything that can be squeezed out of the US NCDB database, which is garbage.

 

[Gfunk6]

The French public health system installed tomotherapy at 3 sites, distributed in the country. Of course the tomotherapy machine was installed each at the leading local site.
So when the article states that 166 patients were treated in 14 sites (74 tomotherapy + 92 RapidArc), it's actually 74 tomotherapy-patients at 3 sites and 92 RapidArc patients at 11 sites. All of them treated over a time frame of 2 years, meaning: 12 patients per site per month in the Tomotherapy-grup (or 1 patient/month) versus 4 patients per site per year in the RapidArc group (or roughly 1 patient every 3 months). I guess that if you do something 3 times more often, you may be able to do it better at some point or at least have the chance to learn how to do it better...

So, it's a matter of expertise / patients volume as well.

Great point, thanks for bringing it up.