SBRT central lung

[CUBuffsgrad98]

What (if anything) are people doing for central lesions in the lung now? What dose?

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[medgator]

10 Gy x 5 for SBRT, 2.5-2.8 Gy/Fx to 70 if doing hypofractionated external

 

[seper]

I'm still not sure if 10 Gy X 5 is safe for truly central lesions, and fractionate over 3 weeks instead.

 

[Neuronix]

10 Gy x 5 fx here as well. The RTOG 0813 trial is trying to evaluate the safety of escalation of that dose, though our institution had a grade 5 event with that trial protocol and stopped enrolling.

My opinion is that even at 10 Gy x 5 fx, you still have to evaluate constraints and sometimes they can't even be met at that dose if the lesion is very central or against critical structures. Those cases are tricky. Then it depends on how much you're willing to sacrifice tumor coverage, treatment intent given life expectancy, surgical candidacy, etc...

Alternatively, the Dutch have had success with 7.5 Gy x 8 fractions, and our lung expert sometimes uses that dose. Is it really safer than 10 Gy x 5 ? I don't know.

 

[medgator]

10 Gy x 5 fx here as well. The RTOG 0813 trial is trying to evaluate the safety of escalation of that dose, though our institution had a grade 5 event with that trial protocol and stopped enrolling.

My opinion is that even at 10 Gy x 5 fx, you still have to evaluate constraints and sometimes they can't even be met at that dose if the lesion is very central or against critical structures. Those cases are tricky. Then it depends on how much you're willing to sacrifice tumor coverage, treatment intent given life expectancy, surgical candidacy, etc...

Yup.... if I get nervous with SBRT for certain central situations, I do accelerated 3DCRT as above (some data for it http://jco.ascopubs.org/content/28/2/202.full.pdf)

 

[Kroll2013]

8* 7.5 Gy ( Dutch Risk adapted regimen)
Waiting for the RTOG 0813 results

 

[ghgi8]

http://www.ncbi.nlm.nih.gov/pubmed/22694017

I would be hesitant to assume 10 x 5 is safe in this situation

 

[RadOncDoc21]

http://www.ncbi.nlm.nih.gov/pubmed/22694017

I would be hesitant to assume 10 x 5 is safe in this situation

Wow, another NEJM publication on RT toxicity!

 

[medgator]

Wow, another NEJM publication on RT toxicity!

it's really just a case report

 

[Palex80]

We do 5 x 8 Gy, but we prescribe this on the 60% PTV-encompassing isodose. This means we are at around 5 x 13 Gy in the GTV area usually. Haven't seen any major toxicity so far.

 

[RadOncDoc21]

it's really just a case report

Let me try to publish my n=1 Stage IIIB NSCLC cure with RT alone in the NEJM... I wish!

 

[medgator]

Let me try to publish my n=1 Stage IIIB NSCLC cure with RT alone in the NEJM... I wish!

To be fair, most of the seminal SCLC studies have been published there

 

[Neuronix]

http://www.ncbi.nlm.nih.gov/pubmed/22694017

I would be hesitant to assume 10 x 5 is safe in this situation

What I've never understood on that paper is the minimal description of the dosimetry. What is the max point dose to the trachea/central airway? What is the V50 for example? The picture given windows the maximum dose to 100%. Was it prescribed to 5 fx x 10 Gy to a point and 50 Gy really is the maximum dose? Or was 50 Gy prescribed to a volume (more likely) and there's a hot spot (how big?) sitting on the central airway? How many people have been treated with central tumors at that institution and so what's the rate of grade 5 toxicity (1%? 5%?), and is there something about the dosimetry in that patient that's different than the other patients? If the mortality rate is only 1%, would we be willing to accept a 1% mortality rate, as the surgeons often do? Don't get me wrong, it's not that this shouldn't be published--the message is loud and clear and needs to get out there. Radiation to the lung can kill people and we need to be really careful.

But that still doesn't leave us with an alternative in that sort of case where the tumor is inoperable. Do we give another hypofractionated regimen with much less data behind it and hope it's safer? Otherwise it's a game of chicken between the tracheal toxicity and the tumor dose, considering 5 x 10 Gy provides the minimum BED to achieve a high rate of control in retrospective series of SBRT. But that also implies that we know a "safe" dose for 5 fraction SBRT on the trachea.

Maybe RTOG 0813 will help clear these things up. In the meantime, I'd be curious in a larger group of attendings, or even thoracic specialists, which treatment option would be the most preferred.

 

[Palex80]

If the mortality rate is only 1%, would we be willing to accept a 1% mortality rate, as the surgeons often do?

1% mortality for centrally located lung tumors (which usually require pneumonectomy or sleeve procedures) is what the thoracic surgeons often wish for. In reality mortality rates after pneumonectomy are quite higher, especially in right-sided procedures. Some series report 20%, some report less. Since many of these patients end up getting neoadjuvant treatment as well, I would say the rate is at least 10%.

Radiation to the lung can kill people and we need to be really careful.

Indeed, but let's be honest: Look at which patients we are getting nowadays for SBRT.
The old, fragile ones.
The ones the thoracic surgeons don't want to operate on.
We were bound to see morbidity and mortality at some point, it was just a question of time.

 

[medgator]

But that still doesn't leave us with an alternative in that sort of case where the tumor is inoperable. Do we give another hypofractionated regimen with much less data behind it and hope it's safer?

I used (and continue to use) 2.5-2.8 Gy to 70Gy in residency for central tumors based on in-house data (http://jco.ascopubs.org/content/28/2/202.abstract?cited-by=yes&legid=jco;28/2/202). There is data to go even higher than that per Fx (per that paper) but that's not something I will do now in practice.

It also endorsed by the NCCN when you check the radiation therapy section in Lung for places without an SBRT program.

 

[medgator]

1% mortality for centrally located lung tumors (which usually require pneumonectomy or sleeve procedures) is what the thoracic surgeons often wish for. In reality mortality rates after pneumonectomy are quite higher, especially in right-sided procedures. Some series report 20%, some report less. Since many of these patients end up getting neoadjuvant treatment as well, I would say the rate is at least 10%.


Indeed, but let's be honest: Look at which patients we are getting nowadays for SBRT.
The old, fragile ones.
The ones the thoracic surgeons don't want to operate on.
We were bound to see morbidity and mortality at some point, it was just a question of time.

Very good points.