Introduction: Formalin is the most commonly used fixative which enables for long-term storage of specimens and preserves morphologic features allowing the microscopic evaluation for future research analysis. Archival collections of the tissue serve as a reliable tool for diagnostic research purpose. They have an important role in on-going patient care, allows for evaluation of recurrent cases for diagnostic purpose and rare case specimens can also be used as an educational tool as well as for further biomedical research purposes. However, studies assessing quality and their usefulness for such purposes are scanty. Hence, the present study is aimed at evaluating and comparing the tissue changes after long-term storage in formalin as well as in paraffin-embedded blocks. Methodology: Three study groups include specimens stored in formalin for a minimum of 5 years (long-term fixed tissue) and their corresponding paraffin-embedded old tissue blocks along with freshly fixed tissues taken as controls which were subjected to routine histopathological procedures and were assessed for macroscopic and microscopic evaluation. Chi-square test and Z-proportion tests were considered for statistical analysis. Results: Prolonged storage of the tissues in formalin showed variation in color and consistency, difficulty in cutting during grossing with inadequate sectioning characters, loss of tissue integrity and architecture, and inadequate nuclear and cytoplasmic details. Conclusion: On histological analysis, prolonged formalin-stored specimens showed deleterious effects than archival blocks. Hence, it can be proposed that tissues are better preserved in paraffin blocks rather than in formalin for further biomedical research purposes.

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Commentary:Oral Squamous Cell Carcinoma (OSCC) has got poor survival rate when associated with lymph node involvement and metastasis. In spite of advanced methods of treatment, mortality rate of OSCC is high 1-3 .The mortality of OSCC is the reflection of metastasis, which complicates the management of a case.Metastasis is the process of dissemination of tumour cells through the circulation which finally get deposited and proliferate to form secondary tumours at a distant site 4,5 . Hence, this intermediate step of tumour cells getting into circulation is an important preliminary step of metastasis. So, early detection and characterization of these Circulating Tumour Cells (CTCs) can be important as a broad-spectrum strategy to monitor, prevent development and manifestation of metastatic disease there by improving the prognosis 2,6,7 . This review aims at understanding the mechanism of CTC, role of detecting CTC in improving prognosis of OSCC, and to understand the recent advances and application of CTC in OSCC.