Survey of current practices from the International Stereotactic Body Radiotherapy Consortium (ISBRTC) for head and neck cancers.

Aim: To provide a multi-institutional description of current practices of stereotactic body radiotherapy (SBRT) for head and neck cancer.
Materials & Methods: 15 international institutions with significant experience in head and neck SBRT were asked to complete a questionnaire covering clinical and technical factors.
Results: SBRT is used 10-100% of the time for recurrent primary head and neck cancer, and 0-10% of the time in newly diagnosed disease. Five centers use a constraint for primary disease of 3-5 cm and 25-30 cc. Nine institutions apply a clinical target volume expansion of 1-10 mm and 14 use a planning target volume margin of 1-5 mm. Fractionation regimens vary between 15 and 22 Gy in 1 fraction to 30-50 Gy in 5 or 6 fractions. The risk of carotid blowout quoted in the re-irradiation setting ranges from 3 to 20%.
Conclusion: There is considerable heterogeneity in patient selection and techniques in head and neck SBRT practice among experienced centers.