Would you recommend adjuvant radiation for a completely resected large well differentiated sarcoma (i.e. liposarcoma) involving the retropharyngeal area and mediastinum?

Here's my take on this. Intrathoracic sarcomas are rare tumors, and there isn't much data to rely on for treatment recommendations. The only study I'm aware of is this retrospective review from University of Washington published in Journal of Radiation Oncology in June 2016

And the only low-grade patients treated in their cohort has positive margins.

I would approach this case like a retroperitoneal sarcoma and not recommend adjuvant radiation.

First off, if you trust your pathologist, and it is a low-grade sarcoma, completely resected, then observation is appropriate.

Second, even if this were a grade 2-3 tumor, or if there were positive margins, since the surgical cavity is now filled with normal structures, delivering 60-66 Gy to this sp...