This article is intended to answer some of the key questions regarding tumor markers for cancer research.

First of all, we will explain what tumor markers are, what they are used for and their main characteristics. Then, we will focus on the main trends in oncological biomarker research, to finalize pointing out the most used markers in different cancer types.

What is a tumor marker?

Tumor biomarkers are molecules mainly produced by neoplastic cells, and under some circumstances also by non-neoplastic cells.

Initially, only proteins overproduced by the cancer cells were considered as tumor markers. However, a wide variety of molecules are now accepted, such as enzymes, hormones, cellular receptors, cytoplasmatic proteins and oncogenes.

There are two major categories of tumor biomarkers attributable to their location: tissue and circulating markers. Tissue markers are expressed in the tissue while circulating biomarkers are present in body fluids.

What are tumor markers for?

Tumor markers give information about the cancer process itself and its malignity. Their applications are the following:

  • Diagnosis.They complement other techniques to reach a final diagnosis. As they might be present in some conditions different than cancer, they are not used alone as a diagnosis tool.
  • Prediction. They are of remarkably useful for building a treatment plan and predicting disease evolution. A decrease on the marker concentration normally means that the treatment is successful.
  • Recurrence monitoring. They provide information about the disease recurrence after a successful treatment.

Does the universal tumor marker exist?

Even though the clinical usefulness of tumor biomarkers is undeniable, nowadays an “universal” marker present in all cancer types does not exist. Some of them, are specific for one cancer type. Nevertheless, others might appear in several.

On the other hand, in some cases, biomarkers that commonly increase in a cancer type, do not change in all the patients. This is the case of the carcinoembryonic antigen (CEA) in colon cancer. It increases in 70-80% of the patients but this percentage decrease dramatically to only 25% for the detection in early stages.

Which are the characteristics of the perfect tumor marker?

The knowledge in this field has increased exponentially in the last years. However, it is of importance to continue researching to find more specific markers, and hopefully the universal marker in the near future.

According to the experts, the ideal tumor marker should be:

  • Highly sensible, allowing the detection of the affected organs exclusively.
  • Deeply specific, being present in a high concentration just in affected patients.

Which are the trends in cancer biomarker research?

Today, cancer research is mostly focus on targeted therapy design, which is commonly known as precision medicine. Besides the study of the function and structure of the markers, these studies integrate modern tools such as transcriptomics and genomics.

The final purpose of these studies is to create novel biomarkers allowing the cancer detection in primary stages of the disease.

One of the latest markers identified, specifically in February 2022, has been AXL tyrosine-kinase receptor. High levels of this circulating biomarker were found in pancreas cancer patients. It allows to discriminate pancreas cancer patients from chronic pancreatitis patients and healthy individuals.

This condition makes AXL marker promising, as it is likely specific for pancreas cancer. However, at the moment, the most used pancreas marker is Ca19-9, highly efficient for treatment follow-up, but poor for detection.

Which are the most used tumor biomarkers used in cancer research?

There are tons of tumor markers, covering the majority of the cancer types. Here are presented the most commonly used biomarkers for the most detected cancer types in Spain, according to the Spanish Cancer Association (AECC), in 2021.

The most frequent cancer type among Spanish population is colon cancer. The carcinoembryogenic antigen (CEA),  is a well-known marker for this cancer type. This biomarker is present inside the organism in the embryonic period. It disappears after birth, except in colon cancer patients and some others.

Another widely used biomarker is carbohydrate antigen 19-9 (CA 19-9), a glycoprotein that increases in colon and bladder cancer patients. However, this marker is certainly unspecific. Thus, its use is limited to the follow-up.

Lung cancer is the leading cause of death in males suffering cancer, and the third one in females. Among lung cancer biomarkers, the carcinoembryogenic antigen (CEA) is one of the most studied. This is an example of the low specificity of some biomarkers, as previously mentioned, and it is used also in colon cancer.

There are other types of biomarkers in this group, such as squamous cell carcinoma (SCC), cyFra 21-1, or ADH Hormone.

The squamous cell carcinoma (SCC) is a circulating antigen produced by the normal cell metabolism. Nevertheless, in some neoplastic processes, such as lung cancer, this marker is overproduced.

Another example is the cyFra 21-1 cytokeratin marker, a cytoskeleton protein associated to the keratin production.

And finally, the last example of lung cancer is the popularly used ADH hormone. It is an ectopic hormone produced by neoplastic cells, which normally does not produce it. This hormone, is normally expressed in the hypothalamus to control the renal function.

The most recurrent cancer type in Spanish males is prostatic cancer. The most important markers for this cancer type are the specific prostatic cancer (PSA), and the prostatic acid phosphatase (PAP) enzyme. Both are proteins secreted in higher concentrations by neoplastic cells than by non-neoplastic cells.

Nonetheless, the most frequent cancer in western females is breast cancer. The mucin glycoprotein encoded by the muc-1 gene, CA 15-3, is one of the most usual breast cancer marker. Another example of breast cancer biomarker is the carcinoembryogenic antigen (CEA), mentioned before in colon and lung cancer sections. Additionally, HER2 growth factor is related to breast cancer. When her2 gene is mutated HER2 protein is overexpressed. This change promotes a faster cell growth and differentiation.

In Abyntek, we are committed with cancer research. In addition to the supply of high-quality research reagents, we also donate part of the benefits to breast cancer research.

All mentioned and more markers, reagents and related products are gathered in our large catalogue. Do not hesitate to contact us and we will be delighted to assist you to find the best products for your research.

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