“…Data were extracted from papers included in the review using the standardised data extraction tool from the Joanna Briggs Institute Meta-Analysis of Statistics Assessment and Review Instrument (Appendix 3) 12 . The data extracted included population, primary treatment modality, salvage treatment modality, subsite of malignancy, tumour–node–metastasis (TNM) classification at the time of salvage surgery, malignancy stage at the time of salvage surgery, p16 status, mortality rate, time to recurrence, post-operative complications and factors associated with mortality.…”