The Study: Here we have the MSKCC approach to de-escalating radiation in this population. Emphasis on the DE. All gross disease is delineated and expanded 5 mm geometrically to create the planning target volume…. Yes, that’s right, the PTV. Which is still prescribed 70 Gy in 35 fractions. The low-risk volume encompasses the ipsilateral and usually contralateral neck nodes and includes a margin approximately 1 cm around gross disease. Ipsilateral nodal regions exclude levels IB and V (and even IV when cN0), and contralateral regions also exclude the retropharyngeal spaces. Here’s the real kicker: the low-risk volume is prescribed 30 Gy in 15 fractions. While this all is beautifully synthesized from existing data and is currently the MSKCC “standard of care,” there are some serious caveats to consider. First, patients have to have HPV-driven disease. Second, they have to be receiving high-dose concurrent cisplatin. Third, they have to have PET/CT and MRI staging. Fourth, they have to have Nancy Lee.
Bottom Line: Radiation dose and volume de-escalation in the setting of high-dose cisplatin for low-risk oropharyngeal cancer is intriguing, but a randomized trial would be nice prior to widespread adoption. | Tsai, Pract Radiat Oncol 2018