Extracapsular extension is a poor predictor of disease recurrence in surgically treated oropharyngeal squamous cell carcinoma.

Extracapsular extension in squamous cell carcinoma nodal metastases usually predicts worse outcome. However, there are no standard histologic grading criteria for extracapsular extension, and there have been few studies on oropharyngeal squamous cell carcinoma alone. We studied the extent of extracapsular extension utilizing a novel grading system and correlated grades with outcomes while controlling for p16 status. A cohort of surgically treated oropharyngeal squamous cell carcinoma cases were reviewed and metastases graded as 0 (within substance of node), 1 (filling subcapsular sinus with thickened capsule/pseudocapsule, but no irregular peripheral extension), 2 (≤1 mm beyond capsule), 3 (>1 mm beyond capsule), or 4 (no residual nodal tissue or architecture; 'soft tissue metastasis'). There were 101 cases, for which p16 was positive in 90 (89%). Extracapsular extension grades did not correlate with nodal size (P=0.28) or p16 status (P=0.8). In follow up, 10 patients (10%) had disease recurrence with only 3 of 64 (5%) grade 0-3 cases and 7 of 37 (19%) with grade 4 recurring (P=0.04). Grade 4 extracapsular extension was associated with poorer survival (P<0.01). However, grade 4 extracapsular extension correlated with higher T-stage (P=0.02), and in multivariate analysis, was not significantly associated with poorer overall (P=0.14) disease-free (P=0.2), or disease-specific survival (P=0.09). The impact of extracapsular extension in nodal metastases is limited in oropharyngeal squamous cell carcinoma. Only extracapsular extension grade 4 associates with poorer outcomes, but not independently of T-stage and other variables.