BACKGROUND:Oral squamous cell carcinoma (OSCC) is a multifactorial malignant epithelial neoplasm. Tumor clearance at the surgical margins in OSCC is a critical factor which strongly influences both the local recurrence and overall survival rate. A quick and accurate intraoperative diagnostic procedure can make a significant difference to the survival rate. Touch imprint cytology (TIC) has commonly been used in the past for the diagnosis of tumors and the detection of sentinel lymph node metastasis. It is routinely applied for intraoperative margin analysis of breast lumpectomy specimens, where it has been proven to have a good success rate. The effectiveness and reliability of TIC in the intraoperative margin evaluation of OSCC, however, has not been established so far. OBJECTIVE:To investigate the diagnostic accuracy of the intraoperative TIC technique for assessing surgical margins in OSCC in comparison to paraffin-embedded hematoxylin and eosin-stained sections. MATERIALS AND METHODS:Thirty previously untreated, biopsy-proven OSCC patients undergoing surgical treatment between December 2008 and September 2010 were included. Patients diagnosed with histological variants of squamous cell carcinoma (SCC) or recurrent tumor were excluded. Three hundred forty-eight touch imprint slides were prepared from 174 margins of 30 resected tumor specimens. Imprints from tumor proper were taken as positive controls. The slides were reported as positive, negative or suspicious for tumor. After all cytological interpretation was completed, the results were compared with the corresponding histological diagnosis. RESULTS:This pioneer study showed that TIC has an overall accuracy of 83%, sensitivity of 91.1%, specificity of 74.4%, positive predictive value of 79.2% and a negative predictive value of 88.6%. The false-positive margins evaluated by TIC were 43 (12.3%) and the false-negative ones were 16 (4.6%). CONCLUSION:TIC is a quick, simple, inexpensive, highly accurate and reliable intraoperative technique to assess surgical margins in SCC of the oral cavity.