Treatment response assessment in resistant oral squamous cell carcinoma applying ¹⁸F-FDG PET/CT with reference to the...

The present study examined the efficacy of the ¹⁸F-FDG PET/CT (18F-FDG PET)-based Lugano Classification for Oral Cancer (Lugano-OC) to stage treatment-resistant oral cancer and its utility for predicting treatment responses.

We included 29 oral squamous cell carcinoma (OSCC) patients with disease progression post the primary treatment, who had ¹⁸F-FDG PET scans prior to secondary treatment initiation, and were evaluable via Lugano-OC between April 2013 and September 2022. To adapt Lugano-OC to the head and neck region, we designated the clavicle level, a regional lymph node in oral cancer, as the reference standard and visually evaluated 18F-FDG PET accumulation patterns. The primary endpoint was the best overall response, which was assessed according to the Response Evaluation Criteria in Solid Tumors.

Patients were categorized into a responder group (n = 7) and non-responder group (n = 22). A univariate analysis revealed significant differences in the CT maximum diameter and metabolic tumor volume (p = 0.050, and 0.037, respectively). A multivariate Cox regression analysis revealed a correlation (hazard ratio 3.59, p = 0.046, 95% confidence interval 1.02-12.6) between Lugano-OC and the duration of treatment responses.

Among OSCC patients with disease progression post the primary treatment, those with Lugano-OC-localized disease who received radiation chemotherapy had a significantly longer treatment response than patients with advanced-stage disease. These results suggest the predictive value of Lugano-OC for assessing treatment responses in this patient population.