Number Needed to Treat Analysis for Planned Neck Dissection after Chemoradiotherapy for Advanced Neck Disease

Objective: To analyze how many planned neck dissections (PNDs) must be performed to prevent one fatal neck recurrence after chemoradiotherapy for head and neck cancer with regional metastasis. Methods: A systematic literature review of studies using chemoradiotherapy as primary treatment for head and neck cancer was performed. Data were extracted where possible to determine estimates for the following variables: (1) percentage of N2-3 necks still harbouring cancer after chemoradiotherapy as proven by pathology from neck dissection (C); (2) percentage of regional recurrence after PND (P); (3) percentage of regional recurrence after salvage neck dissection for patients without initial PND in whom neck disease recurred after chemoradiotherapy (S); and (4) mortality rate of PND (M). The number needed to treat was calculated using the following equation: NNT = 1/[C*(S+M) - (P+M)]. Results: The number needed to treat is 7.5. Conclusion: To prevent one fatal neck recurrence after chemoradiotherapy for head and neck cancer with N2-3 disease, one would need to perform 7.5 PNDs. The results of this study will aid surgeons and patients in making more informed decisions regarding neck dissections.