Intraoperative frozen section histological analysis of resection samples is useful for the control of primary lesions in patients with oral squamous cell carcinoma.

To ensure reliable surgical margins, intraoperative frozen section histological analysis (FS) has been performed since October, 2005 as follows: i) the orientation at the anatomical position and extent of the tumor are shared between oral pathologists and oral surgeons using imaging evaluations and pathological pictures and the planned site of sampling for intraoperative FS is confirmed; ii) a tumor team is organized and the team marks the tumor area and sets the resection range to correct the setting errors of the resection range among operators; iii) vital Lugol staining is applied to the lesion prior to tumor resection, the surgical margin is set based on the non-stained region and the extent of the tumor is macroscopically confirmed in the maximum cross-sectional surface of the resected specimen; and iv) FS is performed using samples from resected specimens to confirm the mucoepithelium and safety margin of the deep stump. The aim of this study was to evaluate the usefulness of our FS method. The treatment outcomes of oral squamous cell carcinoma were retrospectively investigated in patients treated prior to (Group 1) and after (Group 2) the introduction of our FS method. The recurrence rate of the primary lesions was high (17.3%) in Group 1, but decreased significantly in Group 2 (6.9%). Regarding clinicopathological factors, the condition of the surgical margins was associated with recurrence of the primary lesion in Group 1, but not in Group 2. In conclusion, our FS method appears to be useful for resecting tumors with reliable safety margins.