Nasopharynx re-irradiation

[bonusking]

Hello everyone,

I have some questions about Nasopharynx re-irradiation.

What is the criteria to choose the prescribed dose for re-irradiation ?

I have a 66 years old patient that was irradiated in 2010 at 70 Gy using 2D Technique, the recurrence in 2018 was right sided infiltrating the skull base, I think to re irradiate using tomotherapy system up to 63 Gy.

Do you think it is a reasonable approach ?

Thanks.

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[nkmiami]

yes. RTOG actually had re-irradiation study for head and neck, and nasopharynx is probably the most tolerant for re-irradiation. Generally, when I re-irradiate, I try to have pt come bid (1.2 bid) Usually criterea are that pt is 1-2 years out from original treatment.

 

[Gfunk6]

I assume this is a solitary recurrence?

Then I agree it is reasonable with several caveats:

1. Try to perform a composite dose reconstruction if you can
2. Look carefully at dose to spinal cord/brainstem to avoid overdose. The tricky part is to figure out how much the CNS has "recovered" from prior radiation. 8 years is a long time, you can probably assume that the CNS "remembers" 25% of the original Rx dose
3. Be careful with fractionation. Would consider 1.8 Gy/fraction or, if possible, consider hyper-fractionation with 1.2 Gy bid.
4. No concurrent chemotherapy
5. If recurrence is small, may consider an SBRT-type approach
6. Make sure you consent patient thoroughly about potential for catastrophic risks

 

[seper]

Extremely risky to take nervous system parts to > 150 Gy, so I always force the patient to assume ownership of the process.

 

[Radiator20]

Did pt get chemo previously? Particularly if not, I wonder if there would be any role for starting with induction chemo. Of any H&N site, NPX seems to have the clearest benefit in the up-front setting (27686945). I recognize this is not like the trial both because it’s a recurrence and because patient won’t go on to receive concurrent chemoRT. Even so, there might be benefit (maybe all the more if it’s the only systemic tx he’ll see), it may downstage a bit prior to RT, and it will certainly buy you some time to think.

Depending on the location of the recurrence and its relationship to prior treatment field, there might—or might not—be a benefit to protons. Obviously you won’t spare anything in your new target volume but adjacent OARs could be a different story. Have a feeling I’ll get eviscerated for saying it, but skull base re-irradiation does not seem like the craziest scenario to consider it if feasible.

Assume you already have it, but pre-tx MRI and EBV titer will be important.

 

[BobbyHeenan]

Did pt get chemo previously? Particularly if not, I wonder if there would be any role for starting with induction chemo. Of any H&N site, NPX seems to have the clearest benefit in the up-front setting (27686945). I recognize this is not like the trial both because it’s a recurrence and because patient won’t go on to receive concurrent chemoRT. Even so, there might be benefit (maybe all the more if it’s the only systemic tx he’ll see), it may downstage a bit prior to RT, and it will certainly buy you some time to think.

Depending on the location of the recurrence and its relationship to prior treatment field, there might—or might not—be a benefit to protons. Obviously you won’t spare anything in your new target volume but adjacent OARs could be a different story. Have a feeling I’ll get eviscerated for saying it, but skull base re-irradiation does not seem like the craziest scenario to consider it if feasible.

Assume you already have it, but pre-tx MRI and EBV titer will be important.

I agree with protons here. I think there's probably a benefit here and would send this patient for an assessment with a proton center if they have the means/ability to travel.

 

[Palex80]

If the tumor is infiltrating the skull base now and the 2010-series was 2D, you are running into a considerable risk to cause temporal lobe necrosis next to problems with chiasm, brain stem, etc...
2D technique means temporal lobe received > 90% of dose back then.