Stage III NSCLC contouring question

[Gfunk6]

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I have a very fit gentleman with Stage IIIA NSCLC. PET showed a ~ 5.5 cm RLL mass which was biopsy proven to be an adenocarcinoma. PET was negative for LNs or distant disease. He underwent a mediastinoscopy which demonstrated 5 out of 7 positive LN in levels 4 & 7. Due to multi-station disease he was recommended to undergo definitive chemoXRT.

He still does not have pathologically enlarged LNs on planning CT. Per RTOG 0617, I am treating primary lung disease to 60 Gy in 30 fractions. However, what should I do about the LNs? Technically, I should leave it be since there is no anatomic correlate. Would anybody include LNs in the treatment field? If so, to what dose and what LN stations?

 

[Damn_Daniel]

I would surely treat both involved regions, and then ipsi level 2 (upper and lower paratracheals). You definitely know disease is there. Let's not leave it behind. 60/30.

DD
"Making contouring great again"

 

[Cancerdancer]

Yep, cover the involved stations.
A lot of heterogeneity in what we do in lung. For upfront as you state data suggests gross disease alone.
However if this person went to surgery and had LNs found incidentally you'd offer PORT and treat the involved stations plus a large elective volume to 50 Gy. So we as a field we clearly think there is value to treating microscopic nodal disease, it's just a matter of what you can get away with. Less costly in PORT setting.
Depending on cranial/caudal location of the primary, I'd try to cover the primary to 6o-66, plus involved levels to 60, and be a bit generous on what you contour for level 4. The radiographic/bronchoscopic delineations of 2 vs 4 are quite murky.
If that's tough from dosimetric standpoint think reasonable to drop LNs to 50-54 Gy, with either a SIB or sequential boost to primary.

 

[thaddeus]

Agree, would cover nodes. Would include 5&7, plus 4, 8 and probably the inferior part of 3B based on the concept of covering one nodal level above and below the site of known disease. Would try to take to 60 if possible, but dropping to 54 seems reasonable if you can't get an acceptable V20 taking everything to 60.

 

[medgator]

I would treat the involved stations and primary to 60-66. Would not elective cover lymphatics beyond that, although technically, the question of ENI has not been completely settled

 

[Palex80]

60/2 for all involved nodal stations + primary. Boost primary if you can to a dose of 66-70 Gy, use adaptive planning if you can after 50/2.
I'd also treat 2R with 50/2.
If you can't boost primary beyond 60/2, I'd consider lowering dose to the mediastinum to 54/2 for affected nodes and 46/2 for elective nodes (or not irradiate elective nodes at all).
I am calling the odds a lot higher for systemic progression or primary tumor progression than for an isolated mediastinal recurrence/progression.

I would delineate 5R & 8R but wouldn't prescribe dose to them actually. Usually they get tons of incidental dose anyway, when you are treating 4R & 7 with a lower lobe tumor. 🙂



My surgeons tend to actually extract the mediastinal nodes when they do mediastinoscopy if they can and not only perform biopsy on them. Check path report to see, if they did that, which may explain why you dont see the nodes on the planning CT.


Interesting case, by the way, thank you for bringing it up. I'd be thrilled to see, what people would do, if that was a left lower lobe tumor... Irradiate 4R & 2R electively too?

 

[Burt Radnolds]

Great case. It's like a hybrid intact/post op situation, meaning you have to tackle some cognitive dissonance to rectify the difference in how we approach these situations. As radiation oncologists, we tend to believe that in the postoperative setting there is a benefit for nodal radiation for N2 disease. However, in intact stage III patients, we tend to believe to only go after what you can see, because we have a hard enough time controlling gross disease and pure elective nodal failures are rare.

I would argue that 60 Gy to the involved nodal stations detected after mediastinoscopy is overkill and may lead to significantly higher lung and heart doses, altering the therapeutic ratio of your treatment. The nodes were low volume, not even abnormal on PET/CT, and removed surgically. I would treat the involved nodal areas more as though they were postoperative. I would do 60 Gy @ 2 to the gross lung disease and 54 Gy @ 1.8 to ipsilateral 4, 7, 10, and probably 2 using simultaneous integrated boost. I think all of the above suggestions are good though and it really just comes down to stylistic differences. The Lung ART protocol is a good place to start in my opinion when trying to decide what nodal levels to cover in these situations, although it is actually a true postoperative trial.

 

[Gfunk6]

All, thanks for the feedback, in the end I proceeded with 60 Gy to gross diseae and 54 Gy SIB to the known LN basins and anatomically adjacent ones.