Intraoperative ultrasound-guided resection of buccal mucosa cancer

Positive margins (<1.0 mm) are frequently observed during the resection of buccal mucosa squamous cell carcinoma (BMSCC) (reported incidence 5-43%). Intraoral ultrasound (US)-guided surgery could improve margin status. This study included 25 patients with BMSCC treated by US-guided resection. Tumour thickness (TT) and narrowest tumour-free margin for five locations per specimen were measured on US and final histology. The US-guided cohort was compared to a historical cohort for margin status and local adjuvant treatment. Good agreement was observed between the histological TT and in vivo US TT (intra-class correlation coefficient 0.90; mean difference 1.3 mm). Margins were positive in seven patients, close in 17, and clear in one. For histological margins <5.0 mm, the receiver operating characteristic (ROC) curve (area under the curve (AUC) 0.73; P < 0.001) showed a sensitivity of 90% and specificity of 26% at margin 7.5 mm on ex vivo US. The mean difference between ex vivo US margins and histology was 1.2 mm. There was no significant difference between the US-guided and historical cohorts for positive margins, free margins, re-resections, or local radiotherapy (all P > 0.05). US seems able to accurately measure TT with a slight overestimation and could be useful for in vivo and ex vivo margin assessment of the specimen. However, there remains room for improvement in achieving adequate resection margins, particularly by achieving US margins of at least 7.5 mm and following the margin information obtained by US during tumour resection. More research is needed to optimize the outcome.