Question about rhabdo for oral boards...

[OTN]

Hey all.

Question about the following scenario:
- H+N (primary site not really that important for this discussion) rhabdo with a single + LN. Embryonal. Resected completely, both primary and LN.

Would you treat only the LN bed to 41.4 Gy? Or...Include the pre-surgical GTV + 2 cm?

What if the tumor was alveolar? Would you treat the LN region to 41.4 Gy and the pre-surgical primary to 36 Gy? Or do you go to 41.4 for both?

I had always assumed there would only be one dose level: That is, even for a completely resected embryonal primary, if +LNs were resected, you would treat both the primary and LN region to 41.4 Gy. Same for alveolar.

However, in my discussion with my oral study partners, I was informed this was not correct.

What do you think?

t

p.s. Yes, for those of you wondering, studying for oral boards is miserable.

---

Members don't see this ad.

 

[HotSeat]

My thought is that your assumption is correct, and i'm basing this off of how the volumes are described in the low risk rhabdo protocol:

"The GTV is defined as the pre-treatment visible and/or palpable disease defined by physical examination, operative surgical findings, computer tomography, or magnetic resonance imaging. However, in general, the initial GTV does not change based on any surgical resection or chemotherapy
response.

CTV (Clinical Target Volume)
For all Clinical Groups, the CTV is defined as the GTV + 1.0 cm (but not extending outside of the patient). The CTV will always include the entire draining lymph nodes chain if the regional nodes are clinically or pathologically involved with tumor.

PTV
For all Clinical Groups, the PTV is defined as the CTV plus an institution specific margin to account for day to day setup variation related to the ability to immobilize the patient and physiologic motion of the CTV. "

This specifies that the primary site and resected nodes will be in the same PTV and thus, are going to the same dose, which per the protocol "all patients with initial nodal involvement (N1) must receive radiotherapy to a dose of at least
41.4Gy."

The only time the protocol specifies a change in the treatment volume is in one clearly stated instance: "Patients with Clinical Group III disease who do not undergo a second look operation may have a second CTV and PTV defined for a cone down
boost. These patients will receive a total dose of 50.4 Gy. However, if they have a radiographic response to induction chemotherapy, then a cone down boost will be given after a dose of 36.0 Gy. This boost volume will be defined as having a CTV of the original GTV at the time of diagnosis plus a margin of 0.5 cm."

So, i'm with OTN.

Disclosure: I dont know anything about peds, have never treated a rhabdo, and am miserable as well.

 

[qwert]

1) Completely resected primary (neg. margins) site is not treated if embryonal histology. Treat to 36 Gy if alveolar, completely resected.
2) Involved nodal region is treated to 41.4 Gy (provided no gross disease is left after initial surgery).

Hey all.

Question about the following scenario:
- H+N (primary site not really that important for this discussion) rhabdo with a single + LN. Embryonal. Resected completely, both primary and LN.

Would you treat only the LN bed to 41.4 Gy? Or...Include the pre-surgical GTV + 2 cm?

What if the tumor was alveolar? Would you treat the LN region to 41.4 Gy and the pre-surgical primary to 36 Gy? Or do you go to 41.4 for both?

I had always assumed there would only be one dose level: That is, even for a completely resected embryonal primary, if +LNs were resected, you would treat both the primary and LN region to 41.4 Gy. Same for alveolar.

However, in my discussion with my oral study partners, I was informed this was not correct.

What do you think?

t

p.s. Yes, for those of you wondering, studying for oral boards is miserable.

 

[Palex80]

In the European CWS protocol, if primary + nodal disease are completely resected and the histology is favorable (such as embryonal RMS) no radiation therapy is given, provided the patient will receive chemotherapy.