The 5-mm margin in head and neck cancer surgery: From uncontrolled historical dogma to personalised surgery

For decades, a histological margin of 5 mm has been used as the practical definition of a "clear" resection in Head and Neck squamous cell carcinoma, particularly in the oral cavity. This short communication revisits the origins of this threshold, ang argues that it is based more on historical convention than on true validation of oncological biology. Although retrospective studies and meta-analyses have reinforced the 5 mm rule, their interpretation is limited by treatment-selection bias since adjuvant radiotherapy was systematically delivered to patients whose margins fell below this value. Furthermore, the 5 mm definition does not consider how residual disease spreads. Available data suggest that front morphology, as determined by the worst pattern of invasion and tumour budding, is associated with the margin width, even though this needs to be confirmed prospectively. Rather than replacing margin distance, which remains clinically useful and validated, these factors could complement it. Integrating these factors into therapeutic decision-making could be a promising way to achieve personalised management.