Advancing Education, Research, and Quality of Care for the Head and Neck oncology patient.
Objectives: Interpretation of margin adequacy in patients with squamous cell carcinoma (SCC) of the palatine tonsil treated with transoral robotic surgery (TORS) remains controversial and variable in practice. We describe margin findings after radical tonsillectomy, including prevalence of close margins. We also provide a novel description of muscle disruption and muscle invasion within these specimens.
Study Design: Retrospective review of patients undergoing TORS radical tonsillectomy for SCC of the palatine tonsil between January 2017 to December 2023 at a tertiary care center.
Methods: Electronic medical records were reviewed for patient demographics, cancer stage, treatment received, and outcomes. Surgical pathology slides were reviewed for margin distance, and evaluated for a positive margin, close margin (<2 millimeters), and clear margin (>2 millimeters). Margin analysis evaluated the presence of pharyngeal constrictor muscle disruption, and muscle invasion. Muscle disruption was defined as any likely iatrogenic cause of muscle violation, namely cautery artifact. In contrast, muscle invasion was due specifically to disease involvement, with tumor infiltrating or located within or beyond the muscle.
Results: Sixty-six patients with SCC of the palatine tonsil were treated with TORS radical tonsillectomy. Fifty-seven (86.4%) were male. Mean age was 59.7 years on the date of TORS. Pathologic tumor stage was categorized as T1 in 31 (47.0%), T2 in 32 (48.5%), and T3 in three (4.5%) patients. Perineural invasion was present in four (6.1%) patients, lymphovascular invasion in 16 (24.2%), and extranodal extension in 16 (24.2%). Thirty (45.5%) patients underwent surgical management alone, 25 (37.9%) underwent adjuvant radiation, and 11 (16.7%) underwent adjuvant chemoradiation. Thirty-six (54.5%) radical tonsillectomy specimens demonstrated close margins, 26 (39.4%) clear margins, and four (6.1%) positive margins. All specimens demonstrated muscle disruption. Twenty-seven (40.9%) specimens demonstrated no muscle invasion, 32 (48.5%) partial invasion, and seven (10.6%) complete invasion. Margin status was not significantly associated with presence or absence of muscle invasion, nor completeness of invasion. Muscle invasion was associated with pathologic T stage (p=0.049), number of involved lymph nodes (p=0.043), and adjuvant treatment received (p=0.016). In contrast, margin status was not significantly associated with pathologic T stage (p=0.064), although it was significantly associated with PNI (p<0.001).
Conclusions: Iatrogenic muscle disruption is universal across radical tonsillectomy specimens. The rates of muscle invasion (59.1%) and close margins (54.5%), defined as ≤2mm, were also high. Muscle invasion was associated with pathologic T stage, number of involved lymph nodes, and adjuvant treatment received. There was no significant association between muscle invasion and margin status in this cohort, although this requires further study. Clear margins as traditionally defined as ≤5mm may not be feasible within the oropharynx.