Abstract
We read with great interest the recent article by Beibel et al on the current research progress on surgical and molecular margins and prognosis of laryngeal carcinoma. The authors performed a review of the recent literature and found that presence of positive margins has been uniformly associated with increased rates of recurrence and metastasis. However, even in the presence of clear histopathologically surgical margins, there might be expression of tumor-related molecular biomarkers that are also associated with recurrence, metastasis, and overall poor prognosis. The authors concluded that novel techniques that will provide the accurate margins of laryngeal carcinomas are urgently needed in order to improve patients’ prognosis. 1
Flow cytometry constitutes a laser-based technique developed to detect and measure physical and chemical cell features and is an essential tool in clinical diagnosis and in basic research. In clinical practice, flow cytometry is normally used for the diagnosis and classification of patients with hematological malignancies; however, its value in solid tumors has received little attention and is underreported. 2 Flow cytometry performs single-cell analysis and allows the detection of aneuploidy and cells distribution among the various phases of the cell cycle, namely G0/G1, S, and G2/M phase fractions. Although standard cell cycle analysis required substantial time, we have developed a fast cell cycle analysis protocol (Ioannina Protocol) that allowed intraoperative use. 2 In brain tumors, this technique allowed within 6 minutes the intraoperative evaluation of glioma margins, assessment of brain tumor grade, and diagnosis of central nervous system lymphoma.3,4 Encouraging results have also been reported in breast cancer. Resection margins can be assessed by means of G0/G1, S, and G2/M phase fractions evaluation and/or presence of aneuploidy. Concerning head and neck malignancies, we have previously evaluated 70 patients, 39 with benign and 31 with neoplastic lesions. Fifty-eight lesions were diploid and 12 aneuploid. Malignant lesions had a mean G0/G1 phase fraction of 78.5% ± 11.5 contrary to 92.4% ± 2.1 of benign lesions (P < .0001). Malignant tumors had significant higher S and G2/M phase fractions. For the discrimination of neoplastic from nonneoplastic lesions, a cutoff value of 88% in the G0/G1 phase fraction demonstrated a sensitivity of 97.4% and a specificity of 90%. Likewise, a cutoff value of 6% in S-phase had a 97.4% sensitivity and 73.3% specificity and a cutoff value of 5%, in G2/M phase fraction, had a 80% sensitivity and 86.7% specificity. More importantly, we used intraoperative flow cytometry to evaluate resection margins in order to evaluate the extent of excision. In resection margins, absence of tumor was verified based on G0/G1, S, and G2/M phase fraction or presence of aneuploidy. In all cases, there was a compete concordance with pathology. 5
Flow cytometers are widely available; cell cycle analysis can be performed at very low cost and without any risk to the patient. We believe that intraoperative flow cytometry, given that allows a single-cell analysis, is a promising technique that may aid the identification of the “true” cancer margins. It is obvious that future studies are definitely needed in order for safe conclusions to be reached, as well as comparative studies of intraoperative flow cytometry with other intraoperative techniques.
