When treating rectal cancer with conventional neoadjuvant chemoradiation (45 Gy to pelvis with boost to 50.4 Gy), what volume do you use for the boost?

Great question. There does seem to be some variation in boost volume, particularly between 3D and IMRT treatments.

At MDACC, we typically use a prone 3 field belly board technique for most rectal cancer patients receiving standard neoadjuvant long-course chemoradiation. The pelvis goes to 45Gy in 2...

We approach this in much the same way as Emma has described. For 3D treatment, you can simply copy the fields and pull MLCs anteriorly in the lateral fields for more small bowel/bladder sparing. Many times they are quite similar to the original fields especially posteriorly on the lateral fields. Th...