Successful Treatment of Adenoid Cystic Carcinoma with the Application of a High-Dose Stereotactic Body Radiotherapy Boost

BACKGROUND: Adenoid cystic carcinoma (ACC) should be treated with a surgical procedure. Unfortunately, in some cases, such procedures are impossible to perform. In that event, radiotherapy can be used as a form of radical treatment, although ACC is established as a radio- and chemoresistant tumour. Therefore, unconventional fractionated radiotherapy needs to be considered. CASE PRESENTATION: Here, we present a case study of a patient with an unresectable tumour of the choanae and nasopharynx treated with a stereotactic radiotherapy boost in combination with conventional radiotherapy. We achieved complete clinical regression after application of a 1 × 18 Gy boost followed by conventional radiotherapy at 50 Gy in 25 fractions. The early and late tolerance of this treatment were positive. During the 2-year follow-up, local and distant recurrence were not detected. CONCLUSIONS: This case represents an individualized, modern and safe approach to unresectable ACC. This is one of the first cases to show the use of a combination of stereotactic and conventional radiotherapy in radical, conservative cancer treatment.