Volume control.

A few weeks back we brought you the DAHANCA guidelines on generating target volumes for head and neck (H&N) nodal tumor volumes. Now they’re back with consensus guidelines for delineating primary tumor volumes for various H&N sites. And when we say consensus, we mean consensus: This new paper includes input from basically every cooperative group out there (except they didn’t ask the QuadShot). The core principle is that the vast majority of H&N cancers spread via direct extension--kudos, growers. In other words, occult disease is most often found within about 1cm of the primary tumor’s edge. Therefore, they recommend a 5 mm expansion from the gross tumor (GTV-P) to create a higher dose target (the CTV-P1). A 5 mm expansion from CTV-P1 (i.e., a 10 mm expansion from GTV-P) creates a lower dose target (the CTV-P2). Don’t worry, though, they keep the showers happy with well written discussions of adjacent anatomy for each site that should or should not be in the CTV expansions. So, regardless of anatomic predilection, this is really something for all rad oncs to geek-out over.