SABR immediately after external beam to lung

[Treat]

Gentleman with oligometastatic disease, just completed external beam 55Gy/20F to central disease.

Would any of you have concerns if this is followed immediately with SABR to a peripheral lung met?

Are there any dosimetric constraints to the composite plan that have been shown to correlate with pneumonitis? I'm not aware of any..

Appreciate your inputs!

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[thesauce]

I wouldn't have any problems with it. You can alpha/beta correct and use standard V20 and V5 constraints, but it's impossible to know how well that really applies to SBRT doses.

 

[nkmiami]

I have done this several times in stage III pts with bad COPD, and small peripheral primaries. There is literature from MDACC on late salvage SBRT , after intitial chemorads for stage III.
(Ironically, the first patient I treated like this failed one year later in the primary- I had treated it with 10 GY x 4)
BTW- I would not use the V5 in lung.

 

[seper]

IMHO, V5 in lung cancer is not very important if it's kept reasonable (<65% in RTOG 0617, as I recall). I see a lot of people letting their V5 to go >90% now, using recent IMRT DVH studies, and I'm worried it hurts patients.

I have done this several times in stage III pts with bad COPD, and small peripheral primaries. There is literature from MDACC on late salvage SBRT , after intitial chemorads for stage III.
(Ironically, the first patient I treated like this failed one year later in the primary- I had treated it with 10 GY x 4)
BTW- I would not use the V5 in lung.

 

[OTN]

I've treated with SBRT to the lung after fractionated RT with no problem. You have to watch for overlap centrally (large airways, esophagus) and along the chest wall, but outside of those issues in my experience it's been tolerated very well.

 

[Gfunk6]

On a similar vein, if you try to do pre-op CRT for Stage III NSCLC in anticipation of surgery and the surgeon determines it is still unresectable, what would you do? If >1.5 week delay after end of CRT, continuing conventional fractionation would probably not help. But full dose SABR probably not wise either.

Thoughts?

 

[evilbooyaa]

IMHO, V5 in lung cancer is not very important if it's kept reasonable (<65% in RTOG 0617, as I recall). I see a lot of people letting their V5 to go >90% now, using recent IMRT DVH studies, and I'm worried it hurts patients.

I think the recent secondary analysis of 0617 is suggesting that V5 < 65% doesn't change the incidence of any grade >= 3 toxicity, hence why you may see people be more lenient with it (in order to minimize V20)

Impact of Intensity-Modulated Radiation Therapy Technique for Locally Advanced Non-Small-Cell Lung Cancer: A Secondary Analysis of the NRG Oncology... - PubMed - NCBI

As to the OP question - I wouldn't have any specific concerns. If it's concurrent, or maybe within 6 months of one another, I'd keep an eye on the EQD2 V20 (I know SBRT BED calcaultions aren't precisely FWIW), which seems to work out to about V12 (assuming 10Gy per fraction, BED = 10)

 

[evilbooyaa]

On a similar vein, if you try to do pre-op CRT for Stage III NSCLC in anticipation of surgery and the surgeon determines it is still unresectable, what would you do? If >1.5 week delay after end of CRT, continuing conventional fractionation would probably not help. But full dose SABR probably not wise either.

Thoughts?

Accept the fact that their outcome is going to be marginally poorer given the 1.5 week break. That's the whole issue with pre-op CRT for the lung; how many cases are deemed unresectable after the 45Gy? At my institution that Albain trial methodology is extremely rare to see precisely because of that issue. Usually in those cases (here), patients are planned for a boost, see the surgeon right at the end of 45Gy, and if are unresectable continue with radiation within 1 to 2 days.

As a corollary, that's probably why you see 50 or 50.4 for Esophageal/GEJ cancers. Off protocol you have to be prepared to deal with a surgeon saying "nope, not taking this guy to the OR" despite what they may have said prior to initiation of chemoRT. Same with rectal cancer, but a LAR seems less morbid than an esophagectomy. Given the Albain trial, likely less morbid than lung surgery too.

 

[medgator]

Accept the fact that their outcome is going to be marginally poorer given the 1.5 week break. That's the whole issue with pre-op CRT for the lung; how many cases are deemed unresectable after the 45Gy? At my institution that Albain trial methodology is extremely rare to see precisely because of that issue. Usually in those cases (here), patients are planned for a boost, see the surgeon right at the end of 45Gy, and if are unresectable continue with radiation within 1 to 2 days.

As a corollary, that's probably why you see 50 or 50.4 for Esophageal/GEJ cancers. Off protocol you have to be prepared to deal with a surgeon saying "nope, not taking this guy to the OR" despite what they may have said prior to initiation of chemoRT. Same with rectal cancer, but a LAR seems less morbid than an esophagectomy. Given the Albain trial, likely less morbid than lung surgery too.

Totally agree. We don't resect stage III lung ca where I practice and I find the concept of neoadj chemo/xrt fraught with problems.... What do you after surgery and preop chemo/xrt with a + margin or ece?

 

[evilbooyaa]

Totally agree. We don't resect stage III lung ca where I practice and I find the concept of neoadj chemo/xrt fraught with problems.... What do you after surgery and preop chemo/xrt with a + margin or ece?

There are times where a stage III N1 or clinically single-node N2 gets neoadjuvant chemo (alone) followed by surgery. That can be followed with PORT if ypN2.


We probably have one patient every few months who is planned for pre-op chemoRT. I think the count is somewhere around 1 out of 6 of those patients that I've seen have actually gone for surgery.

Maybe if they're post-op after neoadjuvant CRT you throw on like 15 - 20Gy in the problem areas, similar to Sarcoma, but even that seems more to treat the physicians' mental psyche than the patient's cancer.

 

[radoncopotamus]

If giving around same time should probably do additive eqd2 to estimate pneumonitis risk. Also, make sure he's not getting chemo overlapped with SBRT, especially if SBRT volume is near any central structures. Otherwise, treat away if adequate lung function.