Radiooncological View on Therapy Outcome after Multidisciplinary Treatment of Sinonasal Tumors

SIMPLE SUMMARY: Tumors of the nasal cavity and paranasal sinus are rare. Most are discovered at a locally advanced stage and require multimodal treatment consisting of surgery and radiotherapy with concomitant chemotherapy. Tumor localization between the eyes and near the brain makes treatment planning difficult due to the necessary consideration of both critical normal tissue with high protection priority and the curative aim of the best radiotherapy dose deposit. Thus, it is noteworthy how tumor volumes impact the five-year survival outcome. Therefore, we investigated initial tumor volumes before any therapy. Patients with larger mean initial tumor volumes of more than 75 cm(3) had worse outcomes. There was no additional benefit of upfront surgery. Especially for patients with large tumor burdens of the nasal cavity or paranasal sinus, an interdisciplinary case discussion with the patient is essential in the process of shared decision-making. ABSTRACT: Purpose: We report the outcome of a mono-institutional retrospective study of sinonasal carcinoma with the primary focus on GTV (gross tumor volume) and the effect of radiotherapy. Methods: 53 patients with sinonasal carcinoma and that of the nasal cavity, paranasal sinus or both except lymphoma were included. All patients were treated between 1999 and 2017. For tumor volume delineation, all pre-therapeutic images were fused to the planning CT (computed tomography). Results: The median follow-up was 17 months [0.3–60], the median age 60 years, 35 males and 18 females were included. Squamous cell carcinoma (SCC) (60.4%) was the predominant histology, followed by adenocarcinoma (15.1%). The mean composite OS (overall survival) time was 33.3 ± 3.5 months. There was no significant difference in the 5 y composite OS between tumor localization or radiotherapy setting. The simultaneous integrated boost concept showed a trend towards improving five-year composite OS compared to the sequential boost concept. The only factor with a significant impact on the 5 y composite OS rate was the pre-therapeutic GTV (cutoff 75 cm(3); p = 0.033). The GTV ≥ 100 cm(3) has no effect on the 5 y composite OS rate for SCC. Conclusions: The pre-therapeutic GTV is a prognostic factor for five-year composite OS for the entire group of patients with sinonasal tumors, influencing the outcome after completion of all treatment strategies. The GTV seems to not influence five-year composite OS in SCC. For this rare tumor entity, an intensive, multidisciplinary discussion is essential to finding the best treatment option for the patient.