Immunoassays are the most commonly used method to measure tumor markers since it is easy to perform and do not require expensive materials or equipment and skills compared to other methods. Tumor markers are detected using capture and label antibodies. Aside from being affected by icteric, lipemic, and hemolyzed samples and antibody cross-reactivity, What are the others inferences or disadvantages of using this method?
Hello Mariah Sophia C. Quisumbing
Apart from the factors that you have mentioned, specificity and sensitivity are the two main factors which will determine the effectiveness of a diagnostic test. Conventional ELISA-based immunoassays may confront a serious sensitivity problem, so low concentrations of tumor markers cannot be identified at the early stages of cancer.
What if there are cancer biomarkers with concentrations below the LOD of ELISA? Then the use of conventional immunoassays excludes any possibility of their detection. To reveal their diagnostic potential, more sensitive immunoassay methods with an LOD lower than that of traditional methods will be required.
The conventional immunoassays with a relatively high LOD will often give false positive results, since cancer biomarkers are present not only in patient samples, but also in healthy subjects. To remove false positives, the threshold concentration of a biomarker should be chosen. Thus, the use of a more sensitive assay to detect known tumor biomarkers becomes necessary.
Best.
Simply put, it lacks sensitivity and specificity however they are still used for tumor markers such as PSA, CA125 and AFP because there are other methods that can help increase their sensitivity and specificity including calculation of their changes over time, measurement of subfractions of these markers that are more cancer-specific, and combinations with other markers or imaging modalities.
Meany, D. L., Sokoll, L. J., & Chan, D. W. (2010, November 1). Early Detection of Cancer: Immunoassays for Plasma Tumor Markers. NCBI. Retrieved February 23, 2023, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2788950/
In terms of colorimetric immunoassays, this method for tumor marker detection usually uses antibodies. However, antibodies with high affinity and low cross-reactivity are very limited. Moreover, nanomaterials utilized in colorimetric methods are currently restricted to Au-NPs and MPs. In addition, because most cancers have more than one marker associated with their incidence, measuring a single tumor marker is usually insufficient for diagnosis.
Reference:
Yin, Y., Cao, Y., Xu, Y., & Li, G. (2010, December 7). Colorimetric immunoassay for detection of tumor markers. International journal of molecular sciences. Retrieved February 23, 2023, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3100837/
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