Immunohistochemistry (IHC) is a widely used technique in pathology that involves the use of antibodies to detect specific proteins in tissue samples. It has been used for various purposes, including the diagnosis and classification of tumors, identification of therapeutic targets, and prediction of treatment response. The accuracy of IHC in predicting the response to chemotherapy has been the subject of several studies, and the results have been mixed.
One of the challenges in using IHC to predict treatment response is the complex nature of tumor biology. Tumors are heterogeneous, and the expression of specific proteins can vary within and between tumors. Additionally, the response to chemotherapy can be influenced by various factors, including the type of chemotherapy, the stage of the disease, and the patient’s overall health status. Therefore, it is unlikely that a single biomarker or IHC assay can accurately predict treatment response in all cases.
Several studies have examined the utility of IHC in predicting the response to specific chemotherapy regimens in various types of tumors. For example, in breast cancer, the expression of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) has been used to predict the response to hormonal therapy and HER2-targeted therapy. However, the predictive value of these biomarkers for chemotherapy response is less clear. Some studies have suggested that high expression of ER and/or PR is associated with a better response to chemotherapy, while others have found no significant association. Similarly, the association between HER2 expression and chemotherapy response is inconsistent, with some studies showing a positive correlation and others finding no significant association.
In colorectal cancer, the expression of thymidylate synthase (TS) and dihydropyrimidine dehydrogenase (DPD) has been used to predict the response to fluoropyrimidine-based chemotherapy. TS is the target of fluoropyrimidine drugs, and high expression of TS has been associated with resistance to these drugs. Conversely, DPD is involved in the metabolism of fluoropyrimidines, and low expression of DPD has been associated with toxicity to these drugs. Several studies have shown that the expression of TS and DPD can predict the response to fluoropyrimidine-based chemotherapy, although the results have been mixed.
In lung cancer, the expression of excision repair cross-complementation group 1 (ERCC1) and ribonucleotide reductase subunit M1 (RRM1) has been used to predict the response to platinum-based chemotherapy. Platinum drugs, such as cisplatin and carboplatin, are commonly used in the treatment of lung cancer, and resistance to these drugs is a major challenge. ERCC1 and RRM1 are involved in DNA repair and nucleotide metabolism, respectively, and high expression of these proteins has been associated with resistance to platinum drugs. Several studies have shown that the expression of ERCC1 and RRM1 can predict the response to platinum-based chemotherapy, although the results have been inconsistent.
Overall, the accuracy of IHC in predicting the response to chemotherapy depends on several factors, including the type of tumor, the chemotherapy regimen, and the specific biomarkers used. In general, IHC can provide useful information about the molecular characteristics of tumors and can help guide treatment decisions. However, it should be used in conjunction with other clinical and pathological factors and should not be relied upon as the sole predictor of treatment response.
In conclusion, IHC is a valuable tool in predicting treatment response, but its accuracy is limited by the complex nature of tumor biology and the variability of treatment response. Future studies should focus on the development of more comprehensive biomarker panels and the integration of IHC with other technologies, such as genomics and proteomics, to improve the accuracy of treatment response prediction.
