Unilateral vs Bilateral Transoral Surgery for Tonsillar Squamous Cell Carcinoma: A Systematic Review and Meta-Analysis.

Importance: Transoral surgery via a radical tonsillectomy followed by pathology-guided adjuvant therapy is standard of care for tonsillar squamous cell carcinoma (SCCa). There is significant variation in the management of the contralateral tonsil without clinical evidence of disease. Objective: To assess the second primary tumor rates, oncologic survival, functional outcomes, and complications between bilateral and unilateral transoral surgery for tonsillar SCCa. Data Sources: A search of Embase, Ovid MEDLINE, Scopus, and Cochrane was performed on September 11, 2024. Study Selection: Inclusion criteria were studies with more than 10 adults undergoing transoral surgery for unilateral tonsillar SCCa reporting at least 1 primary or secondary outcome. Screening of abstracts and full texts along with data extraction were performed in duplicate. Data Extraction and Synthesis: The Meta-analysis of Observational Studies in Epidemiology (MOOSE) reporting guideline was followed. Data were pooled using a random-effects model. Main Outcomes and Measures: The primary outcome measure was the synchronous and metachronous contralateral tonsil second primary tumor rates. Secondary outcome measures were between-group differences in oropharyngeal hemorrhage and gastrostomy tube dependence rates and 2-year and 5-year overall survival (OS) and disease-free survival (DFS). Results: Of 136 unique citations identified, 11 studies were included, representing a total of 1486 patients (634 bilateral surgery, 852 unilateral surgery). The synchronous contralateral tonsil second primary tumor rate in the bilateral surgery group was 4.0% (95% CI, 2.0%-5.0%; I2 = 0.05%). The metachronous contralateral tonsil second primary tumor rate in the unilateral surgery group was 0.1% (95% CI, 0%-1%; I2 = 0.04%). There were no between-group differences in oropharyngeal bleeding rate (-0.2% [95% CI, -5.6% to 5.3%]) or gastrostomy tube dependence rate (-0.5% [95% CI, -5.2% to 4.3%]). The 2-year and 5-year pooled OS proportion differences between the bilateral surgery and unilateral surgery groups were 3.6% (95% CI, -2.2% to 9.4%) and 5.3% (95% CI, -3.8% to 14.4%), respectively. The 2-year and 5-year pooled DFS proportion differences between the bilateral surgery and unilateral surgery groups were -0.5% (95% CI, -6.5% to 5.4%) and 11.1% (95% CI, 1.6%-20.5%), respectively. Conclusions and Relevance: This systematic review and meta-analysis suggests that omission of contralateral elective extracapsular tonsillectomy in tonsillar SCCa is safe with markedly low metachronous contralateral tonsillar second primary tumor rates and no compromise in survival. The decision to perform a simultaneous contralateral extracapsular tonsillectomy can be addressed via clinician-patient shared decision-making with consideration of its pros and cons.