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9. Solid Tumors [Breast and HER2 amp; Lung (ALK/RO ...
C09 Solid Tumors Dubuc Notes
C09 Solid Tumors Dubuc Notes
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Pdf Summary
Cancer is a multi-step process in which acquired aberrations lead to uncontrolled cell growth. Tumor suppressor genes act to restrict and control cell growth, while oncogenes promote and accelerate cell growth. Chromosomal alterations, such as deletions, translocations, and amplifications, play a role in the development of solid tumors. Cytogenetic analysis coupled with histopathology diagnosis has allowed for the identification of recurrent pathognomonic changes in various solid tumors.<br /><br />There are challenges with chromosome analysis, including microbial contamination, tumor necrosis, overgrowth of reactive cells, and variable growth. FISH-based testing has overcome some of these limitations by allowing the evaluation of fixed material and non-dividing cells. However, FISH analysis requires prior knowledge of expected findings and may not capture deletions effectively.<br /><br />Testing options for solid tumors include FISH and karyotyping. Pathognomonic findings can be rapidly diagnosed with FISH, while patterns of chromosomal alterations can provide information in the absence of pathognomonic structural rearrangements.<br /><br />The chromosomal alterations in specific tumors have been identified, such as the KIAA1549-BRAF fusion in pilocytic astrocytoma and the del(3p) and +12 in renal cell carcinoma. Algorithms used for copy number detection require the aberration to be present in more than 30% of cells.<br /><br />Microarray analysis allows for genome-wide evaluation of copy number and structural variations. However, it requires in vitro growth and may be suboptimal for low-tumor content samples. HER2 testing in breast cancer involves incorporating immunohistochemistry (IHC) and FISH.<br /><br />In conclusion, cytogenetic studies have contributed to the understanding of solid tumors by identifying pathognomonic structural rearrangements and copy number alterations. FISH, karyotyping, and microarray analysis are valuable tools in diagnosing and characterizing solid tumors.
Keywords
Cancer
Cell growth
Tumor suppressor genes
Oncogenes
Chromosomal alterations
Cytogenetic analysis
Histopathology diagnosis
FISH-based testing
Solid tumors
Copy number variations
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