Proton Therapy for Paranasal Sinus Cancer: Clinical Outcomes and Patterns of Failure

Purpose To evaluate the clinical outcomes and patterns of failure in patients with paranasal sinus cancer treated by proton therapy during 2013–2022. Methods and Materials This retrospective study included 88 patients with newly diagnosed nonmetastatic paranasal sinus cancer treated by proton therapy at a tertiary academic cancer center from August 2013 to November 2022. Fifteen patients were treated by three‐dimensional conformal proton technique ( 3DCPT ) and 73 patients were treated by intensity modulated proton therapy ( IMPT ). The main outcomes were the long‐term toxicity, patterns of failure and survival outcomes, including cumulative incidence of local or regional failures ( LRF ) and overall survival ( OS ). Results The median (interquartile range [ IQR ]) follow‐up time for the overall group was 57.3 (38.5–82.6) months. Acute grade 3 radiation dermatitis and late grade 3 nasal congestion occurred significantly more frequently in the 3DCPT group compared to the IMPT group (20.0% vs. 4.1%, p = 0.008; 33.3% vs. 5.6%, p = 0.004, respectively). By the last follow‐up, 33 patients had developed treatment failures. A total of 21 patients (23.9%) developed local failures, 14 were considered in‐field failure; 4 were marginal; 3 were out‐of‐field failure. The 5y‐cumulative incidence of LRF and OS rate of the overall group were 25% [95% confidence interval ( CI ), 16–35] and 79.4% (70.2–89.8), respectively. There were no statistically significant differences following 3DCPT and IMPT in cumulative incidence of LRF and OS . Conclusions Proton therapy yielded excellent therapeutic outcomes in the management of paranasal sinus cancer. IMPT holds significant potential in enhancing the therapeutic ratio in paranasal sinus cancer and warrants further exploration in clinical settings.