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

OBJECTIVE

The present study examined the efficacy of the F-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.

PATIENTS AND METHODS

We included 29 oral squamous cell carcinoma (OSCC) patients with disease progression post the primary treatment, who had F-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.

RESULTS

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.

CONCLUSION

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.