Are there any anatomical locations that you would consider omiting preoperative radiation for sarcoma due to toxicity concerns?

Its a risk benefit discussion. Groin tends to be location with significant risk of toxicity particularly in higher risk patients (elevated BMI, smoker, etc). However, for high grade sarcomas there is a clinical benefit and getting these same patients through post-op can be even more challenging.

I usually use IMRT for these cases with MR sim. I think the has improved volume delineation and allowed for smaller volumes in conjunction with daily image guidance with CBCT. That being said, we still face toxicity in this region and manage it with supportive care and aggressive wound management before and after surgery based on discussion with surgeon.