Cancer Genetics and Epigenetics 2024, Vol.12, No.4, 194-209 http://medscipublisher.com/index.php/cge 199 colorectal cancer with high accuracy, even at early stages (Surinova et al., 2015b). The ability to perform multiplex sequencing enables the simultaneous analysis of multiple biomarkers, increasing the diagnostic power of NGS. This technology also facilitates the monitoring of treatment response and the detection of emerging resistance mutations, making it an invaluable tool in the management of colorectal cancer. 4.3 Digital PCR and qPCR Digital PCR (dPCR) and quantitative PCR (qPCR) are highly sensitive techniques for quantifying nucleic acids, making them essential tools in the detection of non-invasive biomarkers for colorectal cancer. dPCR provides absolute quantification of target DNA or RNA molecules by partitioning the sample into thousands of individual reactions, allowing for the detection of low-abundance targets with high precision. This technique is particularly useful for detecting specific mutations, copy number variations, and methylation patterns in circulating tumor DNA (ctDNA) and RNA. qPCR, also known as real-time PCR, quantifies nucleic acids by measuring the accumulation of the amplified product in real-time. It is widely used for its efficiency and ability to analyze multiple targets simultaneously. qPCR is commonly employed to validate biomarkers identified through other high-throughput methods such as NGS. Studies have shown that both dPCR and qPCR can detect colorectal cancer biomarkers with high sensitivity and specificity, even in early stages of the disease (Vychytilová-Faltejsková et al., 2016). These techniques are also valuable for monitoring treatment response and detecting minimal residual disease, providing critical information for personalized cancer management. 4.4 Immunoassays and ELISA Immunoassays, including enzyme-linked immunosorbent assays (ELISA), are widely used for detecting and quantifying proteins and other biomolecules based on antigen-antibody interactions. These assays are highly specific and sensitive, making them ideal for measuring protein biomarkers associated with colorectal cancer. ELISA is a standard method for validating biomarker candidates identified through proteomic and genomic studies and is commonly used in both research and clinical settings. The technique involves the immobilization of an antigen or antibody on a solid surface, followed by the detection of the bound biomolecule using a labeled antibody. This generates a measurable signal that correlates with the concentration of the target molecule in the sample. Studies have demonstrated that immunoassays can effectively detect various protein biomarkers, such as carcinoembryonic antigen (CEA) and cancer antigen 19-9 (CA19-9), which are associated with colorectal cancer (Chen et al., 2017). The ability to measure multiple biomarkers simultaneously using multiplex immunoassays enhances the diagnostic accuracy and provides a comprehensive profile of the patient's biomarker status. Immunoassays are also valuable for monitoring treatment response and disease progression. 4.5 Mass spectrometry Mass spectrometry (MS) is an analytical technique used to identify and quantify molecules based on their mass-to-charge ratio. In the context of biomarker detection, MS is employed to analyze protein expression, post-translational modifications, and metabolite profiles in various samples. MS-based proteomics is instrumental in discovering novel biomarkers and understanding the molecular mechanisms underlying colorectal cancer. This technique involves the ionization of molecules, separation of ions based on their mass-to-charge ratio, and detection of the ions to generate a mass spectrum. The high sensitivity and specificity of MS allow for the detection of low-abundance proteins and metabolites, which are critical for early cancer detection. Studies have shown that MS can identify unique protein signatures and metabolic profiles associated with colorectal cancer, providing valuable information for diagnosis and prognosis (Qian et al., 2018). MS-based methods, such as tandem mass spectrometry (MS/MS) and liquid chromatography-mass spectrometry (LC-MS), offer comprehensive analysis of complex biological samples, making them powerful tools for biomarker discovery and validation.
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