Prevalence of synchronous bilateral/contralateral tonsil carcinoma: A systematic review and meta-analysis.

The purpose of this systematic review and meta-analysis was to identify the prevalence of synchronous contralateral tonsil carcinoma (SCTC) amongst patients with tonsil carcinoma or head and neck squamous cell carcinoma of unknown primary (HNSCCUP). Thirteen retrospective studies, comprising 2623 patients, were analysed, revealing an overall pooled SCTC prevalence of 4%, rising to 10% in HNSCCUP cases. HPV/p16 positivity was associated with SCTC prevalence of 3%, while HPV/p16 negativity was greater at 8%. Clinical or imaging evaluations often missed SCTC preoperatively, emphasising the importance of contralateral tonsillectomy. Morbidity varied among patients undergoing contralateral tonsillectomy. The prevalence of SCTC is significant in cases of HNSCCUP and tonsil malignancy, emphasising the importance of informed discussions regarding contralateral tonsillectomy. Tailored approaches considering individual patient and tumour characteristics are crucial, with contralateral tonsillectomy generally warranted in HNSCCUP. Further research, including prospective studies with standardised protocols, is needed to improve the understanding and management of SCTC, specifically the clinical significance of occult SCTC.