Relationship between extracapsular spread and FDG PET/CT in oropharyngeal squamous cell carcinoma

Median maximum standardized uptake (SUVmax) cut-off values of FDG PET/CT higher than 3.85 were found to be associated with a greater risk cervical lymph node metastasis with extracapsular spread (ECS) in patients with oropharyngeal squamous cell carcinoma (OPSCC).

The purpose of this study was to evaluate the use of FDG PET/CT for the identification of ECS and to establish its histologic correlates in OPSCC.

The medical records of 78 patients who underwent FDG PET/CT for OPSCC before surgery were reviewed.

ECS was present in 42% (42/69) of dissected necks and in 51% (54/106) of dissected cervical levels. The SUVmax values of cervical lymph nodes with and without ECS were found to be significantly different (6.73 ± 3.78 vs 3.02 ± 2.24, p < 0.001). The SUVmax cut-off value for differentiating necks with ECS from those without ECS was 3.85. The presence of ECS (p = 0.036) and median SUVmax (using 3.85 as a cut-off) (p = 0.037) were found to have a significant adverse effect on 5-year disease-specific survival by univariate analysis. The multivariate analysis showed a significant association of 5-year disease-specific survival with ECS (hazard ratio (HR) = 32.3 in cervical metastasis with ECS, p = 0.012; and HR = 19.6 in cervical metastasis without ECS, p = 0.024).