Fig. 1

Adjuvant chemoradiotherapy for a CCUP in a 70-year-old male patient. (A) Pretherapeutic sonography, CT and MRI imaging (a) in December 2017 showed a pathological lymph node in level IIa on the left side and a suspicious lymph node in level II on the right side. A panendoscopy with multiple biopsies of different mucosal regions revealed no primary tumor. As the patient had a tonsillectomy as child, no additional tonsillectomy was performed. The recommended FDG-PET-CT was not conducted, as the costs were not covered by the patient’s health insurance. After bilateral ND in January 2018, pathological assessments showed one necrotic lymph node (1.4 cm diameter) with poorly differentiated (G3), HPV-positive squamous cell carcinoma cells in left-sided level IIa, giving a cTx pN1 cM0 CCUP according to the 7th Edition of the UICC TNM classification. Based on the recommendations of the multidisciplinary tumor board, an adjuvant cisplatin-based chemoradiotherapy with intensity-modulated radiotherapy was performed between March and April 2018. The elective lymphatic drainage and mucosa received 50 Gy in 25 fractions, while the high-risk PTV was treated with a sequential boost of 10 Gy delivered in 5 fractions. (b, c and d) Dose distribution of a volumetric modulated arc therapy plan in an axial (b), sagittal (c) and coronary (d) scan image. The last follow-up in March 2019 showed no signs of recurrence