Acetic Acid and Iodine Staining for Determining Malignancy in Solid Tumors

OBJECTIVE: Surgical margin is an important prognostic factor in solid cancer surgery. Frozen section (FS), the gold standard for intraoperative surgical margin evaluation, requires extensive waiting time and expensive FS devices. The purpose of this diagnostic study was to verify whether multi-staining (MS) method with acetic acid and iodine could be used to differentiate malignant and non-malignant lesions of solid tumor. METHODS: The study was conducted on patients with solid tumor who underwent surgery in the Surgical Oncology Division of Dr. Cipto Mangunkusumo General Hospital from December 2017 to April 2018. Samples measuring less than 5 mm, necrotic tissue sample, and patients who did not agree to participate in the study were excluded. Every specimen was divided into two, one side as unstained control and the other side as MS samples. MS samples were sprayed with 10% acetic acid combined with iodine. MS samples and unstained controls were sent for histopathologic results and the pathologist was blinded to group assignment. Acetowhitening reaction in the sample was an indication of a positive MS result, and the presence of malignant foci in the histopathology examination was classified as positive pathological results. RESULTS: Five-hundred-and-twenty samples were obtained from 150 patients. MS method was found to have sensitivity and specificity of 82%, and 63.5%, respectively. In subgroup analysis, we found that MS method has a sensitivity and specificity of 100% and 79.3%, respectively for epithelial breast tumor; 65.7% and 83.3%, respectively for thyroid nodules; and 94.1% and 33.3%, respectively for oral cavity tumors. MS method reacts positively to solid malignant tumor and negatively to benign tumor and normal tissue (from margin samples). Highest sensitivity was found for breast and oral cavity malignancy, and high specificity was found for thyroid cancers. CONCLUSION: This study provided an alternative staining method for intraoperative macroscopic surgical margin evaluation, especially for rural areas without frozen section facilities.