Inbetweeners.

Top Line: What are common practices in using an intermediate dose volume in head and neck treatment plans?

The Study: Many of us use a simultaneous integrated boost (SIB) approach when planning definitive radiation for head and neck cancer. Almost all definitive head and neck plans consist of a high risk target volume encompassing gross disease that typically receives ~70Gy in 33-35 fractions and a low risk volume that typically receives ~56Gy. An area of great variation and constant debate is the use of an intermediate risk volume that receives an intermediate risk dose on the order of 60-63Gy. This paper discusses those variations in practice guidelines, protocols, and among head and neck cancer experts. Let’s start with the commonalities. All protocols and experts use an intermediate dose volume surrounding the nasopharynx primary site and involved nodal stations. The next most agreed upon site was the larynx and hypopharynx where all experts used intermediate dose volumes to encompass the entire larynx and 3 out of 4 encompassed the hypopharynx primary site and involved/adjacent nodal stations. In the oropharynx, there was pretty much every variation in covering or not covering the primary and/or nodal stations. When it came to non-nasopharynx NRG protocols, older protocols allowed investigator discretion in using intermediate dose volumes. However, the more recent trials do not allow 60-63Gy volumes. Instead, they either have lower dose (<60Gy) “intermediate dose” volumes or no intermediate dose volumes at all.

TBL: Use this summary the next time you’re debating whether to include a third intermediate dose volume in your head and neck treatment plan. | Freedman, Pract Radiat Oncol 2022