Lymph nodes coverage for Ademoid cystic

[Kroll2013]

Dear friends,

For an adenoid cystic pT4aN0 (cN0 and only level Ia, bilateral Ib were dissected) of the soft palate, what volumes do you cover with postop RT:

1- only the tumor Bed

2- the tumor bed and prophylactic dose to bilateral neck


???


Ty

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[maruchan]

I would cover the neck. For a T4 ACC, the risk of nodal relapse is actually fairly substantial (SAGE Journals: Your gateway to world-class journal research and https://onlinelibrary.wiley.com/doi/full/10.1002/hed.23711) and the patient did not have a complete neck dissection.

 

[scarbrtj]

Cover nodes. Not because it's the right answer, not because there's compelling data... but because ACC has a wildly unpredictable course with varying biologies tumor to tumor. There's an outside chance doing some ENI may make a difference. Yet for example, 5y OS was 65% for cN0/pN+, but a not much better 73% for cN0/pN0 (the p=0.017 is not significant here IMHO and shouldn't convincingly inform you that low volume N+ necessarily does worse); this trend of N+ not doing much worse in ACC is seen in tracheal ACC e.g. HOWEVER... cover the nodes.(Yet, you may argue and say that local recurrences and distant recurrences >>>>> nodal recurrences here for cN0 patients... and you'd be right.)

BTW @maruchan, none of the studies you cite give insight into nodal relapse risk per se for a cN0/pN0 patient.

 

[seper]

also a portion of the base of skull - classic rule

 

[ramsesthenice]

Dear friends,

For an adenoid cystic pT4aN0 (cN0 and only level Ia, bilateral Ib were dissected) of the soft palate, what volumes do you cover with postop RT:

1- only the tumor Bed

2- the tumor bed and prophylactic dose to bilateral neck


???


Ty

I would treat the nodes but admittedly I am torn. I have seen two patients with neck failures in the last couple years (one parotid primary, one tracheal) so on the one hand that says maybe yes. Problem is, the parotid patient had ENI upfront and still failed. I wonder based on biology if 50-54 is enough dose even for elective ENI in AC. I would do it with the “hope” it helps but my confidence would admittedly be low.

 

[evilbooyaa]

With incomplete neck dissection, I'd plan to treat II-III at least. Why is it T4a (Hard palate invasion? Mandibular invasion?), because covering the nerves in that area is of greater importance given the histology. If both SMGs are removed then radiating IB has minimal toxicity. Try to spare B/L parotids as much as possible, meaning keeping top border of level II coverage lower than all the way to skull base (although you'd want to follow any nerves up to skull base)

 

[emt409]

Kind of important to know the PNI status of the tumor for coverage here.

 

[seper]

is it true? I've always presumed microscopic PNI is present for adenoid cystic