volume definition for lung ADK radiation trt after neoadjuvant CT?

[Kroll2013]

48 yo female, stage IIIB Rt Lung ADK, who received 6 cycles of neoadjuvant ChemoT
with very good response on Pet CT post CT
residual active mediastinal and Rt hilar Dz
She is planned to continue with concurrent chemorad

Question: she had a solitary parenchymal tumoral nodule that was Pet + on the pre-Chemo evaluation
and that became Pet negative post neo-adjuvant chemo, with remaining fibrotic image .
should it be taken into the treatment field or should I stick to treating only Pet+ residual dz ?
( knowing that taking this nodule significantly increases doses received by the ipsilateral lung V5-V20-V30)

thank you !

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[OTN]

I've never seen a patient with Stage III NSCLC receive "induction" chemo prior to chemorads. Is there good data for induction chemo prior to chemoRT? Is anyone else doing this at their institution? We're still sticking with chemoRT definitively.

Anyway, my inclination would be to tx all the PET-avid disease which was present initially, but I would really have to take a look at the induction protocols to see what was done to generate the data you're using to justify induction chemo.

 

[medgator]

No good data to support induction unless pre surgery but obviously not the case here

 

[Cancerdancer]

If you're treating chemorads now you're obviously doing so in attempt for cure. You therefore need to treat all areas that were initially involved; chemo alone won't render those areas disease free. You can likely treat as we do for lymphoma with post chemo volumes in the nodes, but you need to treat all nodal stations initially involved. How to treat post-chemo parenchymal disease is less clear; I probably would fuse the original CT and contour that GTV with a PTV margin with the chemo response probably obviating the need for a CTV expansion.
I have treated with induction chemo in the occasional 3b patient where DVH criteria will be hard to meet based on initial disease extent. It's not supported by data, but can allow for tolerable (chemo)RT to be delivered if a response is seen. While some may argue against this, one could likewise argue that stage IIIb patients should be treated with chemo alone and just skip the RT altogether...

 

[Neuronix]

I'm assuming the nodule is far away from the rest of the disease. It depends on how bad the dvh looks. If you can't meet constraints, I'd probably observe the nodule for now and cautiously treat with sbrt or wedge later if it grows and patient is still otherwise alright/non-metastatic.

This assumes you've tried imrt, and reducing CTV/PTV to something minimally acceptable. You could also try a shrinking field technique. I'd want to get all the prechemo disease to 46, then you could re-sim at 30 Gy and boost the residual to 60 Gy. Thus all depends on how marginal you were on constraints in the first place.

 

[seper]

If induction chemo was given because disease extent was too massive, one may choose stick to palliative mode here, and treat residual gross disease + margin.

 

[ramsesthenice]

Agree that induction is weird. I agree with neuronix. If the nodule is far away I'd really think about SBRT for it and conventional to hilum and mediastinum. I would not ignore it because it's PET negative now. If your going to treat definitive treat definitive.

 

[radtothebone]

As a strategy to improve outcomes induction chemo has two trials CALGB (PMID 17404369) and LAMP (PMID 16087941) that showed no benefit prior to ChemoRT. However, like Cancerdancer stated its a reasonable strategy to much unsafe volumes reasonable or to allow a Stage IIIb patient to declare themselves as Stage IV without enduring futile ChemoRT. I also agree with the approach of SBRT to the parenchymal lesion following standard fractionation to the nodal disease.