ENI for NSCLC

[CAbroiler]

Trying to interpret what involved nodal irradiation means with regard to definitive chemoRT for our NSCLC pts with positive mediastinal nodes.

At one site of practice, we generally will contour our primary tumor and put a GTV to CTV expansion (usu around 1cm) on that and then contour any nodes that are positive (either by PET, sampling or over 1cm by CT) and put a margin of ~1cm on those and treat those areas to definitive doses >66Gy.

At another site of practice, not only do we cover those involved nodes plus a margin but also cover adjacent nodal "regions" somewhat akin to those mentioned in the Rosensweig MSKCC paper (supraclavicular, superior mediastinal, inferior mediastinal, and subcarinal).

it seems like the first of these is truly INI whereas the 2nd somewhat skirts between ENI and INI. what do you all do?

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[deleted4401]

I do: primary tumor + 0.6-0.8cm for CTV + 0.5cm and nodes+0.5cm for CTV. CBCT daily, so 0.5cm for PTV, matching to primary tumor.

When I started, had been going to 66-70, but now stopping at 60-63 Gy, as I had a few patients develop RP. I know the data indicates mixed coverage, but I think depending on the way your fields are drawn, the adjacent nodes do get close to microscopic dose and I don't feel uncomfortable at all not including adjacent regional nodes as target.

We've talked about dose before, but for any of you, does the Chinese data make you feel better about going to higher doses? (the ENI to a low dose vs IFRT to a higher dose?)

S

 

[radiaterMike]

The standard (if you base that upon what cooperative group protocols require) is no ENI and treat only gross disease plus margin (which results in 'incidental' ENI). The counter-argument in favor of ENI is well laid out by Dr. Marks in an IJROBP editorial. It would have been nice if the Chinese study were truly a dose escalation study comparing the same radiation fields in both arms.

 

[medgator]

Also important to keep in mind that involved nodal xrt may have some eni related to scattering of the dose.

A good editorial in the Jco:

http://jco.ascopubs.org/content/25/35/5543.full?sid=28acde18-b99b-4c97-96e9-f2bf2d183d3c

Edit: mike beat me to it

 

[Palex80]

SimulD's approach is the way to go, if you choose to ommit ENI. I tend to do the same thing, but try to also encompass the entire lymph node station into the CTV, if there's a node involved in that station.

0.5 CTV to PTV margin is brave, even with CBCT. For a lot of lower lobe tumors I have seen a lot more movement during breathing. The question what to actually match, when you do the fusing is also quite complicated. I heard a lecture by Dirk De Ruyscher from the Netherland a couple of weeks ago on this subject and was quite surprise to see, that we may be fusing on the wrong stuff all the time with CBCT.
Alot has to do with technique as well and whether you are using a 4D-CT or not.

 

[deleted4401]

SimulD's approach is the way to go, if you choose to ommit ENI. I tend to do the same thing, but try to also encompass the entire lymph node station into the CTV, if there's a node involved in that station.

0.5 CTV to PTV margin is brave, even with CBCT. For a lot of lower lobe tumors I have seen a lot more movement during breathing. The question what to actually match, when you do the fusing is also quite complicated. I heard a lecture by Dirk De Ruyscher from the Netherland a couple of weeks ago on this subject and was quite surprise to see, that we may be fusing on the wrong stuff all the time with CBCT.
Alot has to do with technique as well and whether you are using a 4D-CT or not.

Forgot to say one thing. I do inspiration, expiration, and free breathing CTs, then fuse. Then, add 0.5cm. You're right. On just 1 CT, 0.5cm is brave.
S