The Problem of Traditional Diagnostics
Traditional morphological research methods have remained and continue to be the baseline standard in oncopathology for decades. Their essence lies in the visual assessment of tissue and cellular architecture under a light microscope. This classical approach demonstrates high diagnostic value when dealing with differentiated tumors and their metastases. In such clinical cases, tumor cells sufficiently retain the characteristic features of the tissue from which they originally arose, allowing the pathologist to reliably determine the source of tumor growth.
However, in real-world clinical practice, specialists regularly encounter poorly differentiated and undifferentiated malignant tumors. During their development, the cells of these aggressive neoplasms lose their initial specialization to such an extent that visually establishing their tissue origin becomes entirely impossible. It is precisely in this complex diagnostic situation that modern molecular-biological and high-tech morphological methods come to the rescue. They allow physicians to look deep inside the cell—at the ultrastructural and molecular-genetic levels.
Modern Research Methods
An arsenal of advanced laboratory technologies is used to identify the specific characteristics of a tumor cell. Each of the methods listed below solves a narrow diagnostic task, and their well-chosen combination provides specialists with the most complete picture of the disease:
- Immunohistochemistry (IHC): One of the most important methods in modern pathology, allowing the detection of specific antigens directly within a histological tissue section.
- Polymerase Chain Reaction (PCR): A molecular biological method that amplifies specific DNA segments multiple times, helping to identify minimal genetic alterations.
- In situ hybridization (in situ): A unique technology that makes it possible to detect specific nucleic acid sequences directly within cells or tissues while preserving their natural spatial arrangement.
- Blotting analysis: A classical molecular method used for the precise separation and subsequent identification of specific proteins or nucleic acids.
- Cytogenetic analysis: A specialized study aimed at a detailed examination of chromosome structure and the identification of major chromosomal rearrangements.
- Electron microscopy (EM): A morphological method providing immense magnification, allowing the visualization of the minute details of cellular ultrastructure.
Classification of Tumor Markers
Depending on which pathological process, structural element, or cellular mechanism a specific marker reflects, modern pathology generally divides them into six main classification groups:
- Markers of cellular differentiation: Demonstrate which cell type the studied tumor is striving to resemble, even if it appears completely undifferentiated outwardly.
- Histo- and cytogenetic markers: Directly indicate the tissue origin of the malignant neoplasm, helping to determine the primary tumor site.
- Markers of chromosomal and gene rearrangements: Reflect the fundamental genetic mutations underlying the malignant transformation of the cell.
- Markers of altered cell proliferation: Demonstrate the rate and degree of aggressiveness of tumor cell division, which is critical for assessing disease prognosis.
- Markers of cell death (apoptosis): Allow physicians to assess how successfully tumor cells can evade programmed cell death.
- Markers of invasion and metastasis: Characterize the ability of malignant cells to destroy surrounding healthy tissues, penetrate blood vessels, and form secondary foci.