The impact of worst pattern of invasion on the extension of surgical margins in oral squamous cell carcinoma

Background To evaluate margins for oral carcinoma according to types of invasion front. Methods Retrospective cohort of 772 patients with worst pattern of invasion (WPOI) graded 1-5. Local recurrence was the outcome of interest. Results Local recurrences occurred in 164 patients (21.2%) and was affected by WPOI type 4/5, margin distance, perineural invasion, and adjuvant radiotherapy. In patients with WPOI types 1/2/3, a cutoff of 1.7 mm was considered ideal margin extent and in patients with WPOI types 4/5, the cutoff was 7.8 mm. Patients below these thresholds had a significantly higher incidence of local recurrence. Conclusions Different WPOI determine the ideal extent of surgical margins as 1.7 mm for patients with types 1-3, and 7.8 mm in patients with types 4/5.