Vol.:(0123456789) 1 3 European Archives of Oto-Rhino-Laryngology https://doi.org/10.1007/s00405-020-05867-2 HEAD AND NECK Tumor control of cervical lymph node metastases of unknown primary origin: the impact of the radiotherapy target volume Jos M. J. A. A. Straetmans 1,2  · Marijn Stuut 1  · Sanne Wagemakers 1  · Frank Hoebers 3  · Johannes H. A. M. Kaanders 4  · Ernst Jan M. Speel 5  · Willem J. G. Melchers 6  · Piet Slootweg 7  · Bernd Kremer 1  · Martin Lacko 1  · Robert P. Takes 8 Received: 28 December 2019 / Accepted: 12 February 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract Purpose Debate on the extent of treatment of neck metastasis of cancer of unknown primary tumors (CUPs) is still ongoing. In two Dutch tertiary referral centers, the post-surgical radiation target volume changed from the bilateral neck including the pharyngeal axis to the unilateral neck only, in the course of the last decade. This study aims to investigate the outcome of patients with CUP before and after de-escalation of post-surgical radiotherapy. Methods Data of two Dutch tertiary referral centers were merged. Disease-free survival (DFS), overall survival (OS), and regional control rate (RCR) of 80 patients diagnosed with CUP (squamous cell and undiferentiated carcinomas) between 1990 and 2009 were retrospectively analyzed. Results Thirty patients received bilateral neck and pharyngeal axis radiotherapy and 42 patients ipsilateral radiotherapy only. In another eight patients, the postsurgical radiation target volume was expanded to the contralateral neck or to the pharyngeal axis, due to suspicious lesions on imaging. The 5-year DFS, OS and RCR were 60%, 51.2%, and 80%, respectively, in the total patient population. RCR did not difer in patients treated with ipsilateral as compared to bilateral radiotherapy nor did 5-year OS and DFS. No tumors occurred in the pharyngeal axis. Conclusion In this study, omitting elective treatment of the contralateral neck and pharyngeal axis did not lead to a decrease in locoregional control or survival rates when treating patients with CUP. Keywords Lymph node · Pathology · Neoplasms · Unknown primary · Neck dissection · Radiotherapy · Survival rate * Jos M. J. A. A. Straetmans j.straetmans@zuyderland.nl 1 Department of Otorhinolaryngology and Head and Neck Surgery, Research Institute GROW, Maastricht University Medical Center, P.O. BOX 5800, 6202 AZ Maastricht, The Netherlands 2 Present Address: Department of Otorhinolaryngology and Head and Neck Surgery, Zuyderland Medical Center, H. Dunantstraat 5, 6419 PC Heerlen, The Netherlands 3 Department of Radiation Oncology (MAASTRO), Research Institute GROW, Maastricht University, Maastricht, The Netherlands 4 Department of Radiation Oncology, Radboud University Medical Center Nijmegen, Geert Grooteplein-Zuid 22, 6525 GA Nijmegen, The Netherlands 5 Department of Pathology, Research Institute GROW, Maastricht University Medical Center, Maastricht, The Netherlands 6 Department of Medical Microbiology, Radboud University Medical Center Nijmegen, Geert Grooteplein-Zuid 22, 6525 GA Nijmegen, The Netherlands 7 Department of Pathology, Radboud University Medical Center Nijmegen, Geert Grooteplein-Zuid 22, 6525 GA Nijmegen, The Netherlands 8 Department of Otorhinolaryngology and Head and Neck Surgery, Radboud University Medical Center Nijmegen, Geert Grooteplein-Zuid 22, 6525 GA Nijmegen, The Netherlands