Radiological maxillary sinus mucosal extension is associated with prognosis in upper gingiva and hard palate squamous...

Squamous cell carcinoma of the upper gingiva and hard palate (UGHP SCC) often invades adjacent structures, such as the maxillary sinus, which poses challenges for establishing local control. Although maxillary sinus mucosal extension has been suggested as a prognostic indicator, its clinical significance remains controversial because of potential confounding by bone invasion. The data from 66 patients with UGHP SCC, who underwent curative surgery at Hiroshima University Hospital between April 2000 and March 2023, were retrospectively analysed. Preoperative computed tomography (CT)/magnetic resonance imaging (MRI) was used to assess the extension of the tumour, including any vertical extension to the mucosa of the maxillary sinus. Overall survival (OS), disease-specific survival (DSS), and local control rate (LCR) were analysed using the Kaplan-Meier method. To address the potential confounding effect of bone invasion, an additional subgroup analysis was performed that was restricted to tumours with radiological bone invasion (T4). Cox proportional hazards models, adjusted for surgical margin status, were constructed to explore the association with DSS. Radiological maxillary sinus mucosal extension (RSME) was identified in 16 of 66 patients and was significantly associated with poorer DSS and OS. In the subgroup with radiological bone invasion only (n = 27), DSS remained significantly worse in patients with RSME (log-rank test, P = 0.048). The association between RSME and DSS was attenuated after adjustment for surgical margin status.