Breast cancer is one of the most common cancers in the world, and, according to the American Cancer Society, it accounts for 30% of all new female cancers each year. In other words, around 1 in 3 American women with cancer suffer from breast cancer. The median age at the time of breast cancer is 62 in the United States, which means more than half of the women developing the disease are 62 or younger when they were diagnosed.
While incidence rates are increasing marginally per year, there have been great strides made in providing personalized and optimized treatment plans for those with the disease. New technologies have emerged over the years to reduce side effects and to improve patient comfort – and one of these is the increased frequency of biomarker testing as a means of disease monitoring.
A cancer biomarker is a substance or process that indicates the presence of cancer in the body. This substance or process is found in blood, other body fluids, or tissues, and they can be measured and monitored to provide insights into disease development. Some examples of well-known breast cancer biomarkers are Ki-67, CA (Cancer Antigen) 15-3, CA 27.29, and TK1.
Biomarkers are typically retrieved from breast cancer patients in the form of a blood draw, which makes for a relatively non-invasive process compared to tissue biopsies. These biomarkers can provide insights into tumor growth and proliferation, which can lead to valuable information provided on disease development and response to existing treatment plans. This helps guide clinicians make better decisions when devising treatment strategies, and it can reduce patient discomfort when they do not have to undergo unnecessary therapies or take medication that produces no positive effect.
A widely used marker of proliferation, Ki-67, has prognostic value in cancer treatment. (However, Ki-67 is analyzed through IHC when samples are obtained from a tissue biopsy.)Evaluated in several studies over the years, clinicians have discovered the significance of low Ki-67 expression in patients who undergo neoadjuvant chemotherapy. A drop in Ki-67 expression can be seen after 2 weeks of treatment, which can predict short- and long-term outcomes of the patient.
More recent advances have been made in the study of biomarker validity, particularly in investigating the role of TK1 in breast cancer development. TK1 – Thymidine Kinase 1 – is among a group of blood-based biomarkers used for breast cancer monitoring. It is an enzyme that plays a critical role in DNA synthesis. Due to this, it is essentially a marker of cell proliferation, and measurement of TK1 activity can lead to more insights into how fast or slowly tumor cells proliferate.
Studies conducted by various labs around the world have shown that patients with breast cancer demonstrate higher levels of TK1 compared to healthy controls, and higher TK1 activity with poorer cancer outcomes. However, as a relatively new biomarker, the validity and reproducibility of TK1 assessment remains to be fully proven. Nevertheless, serial biomarker testing of TK1 activity has shown promising results as scientists investigate the dynamic changes of TKa following exposure to cancer treatment and its relation to patient prognosis.
Biomarkers not only guide clinicians in building the most suitable treatment strategies for their breast cancer patients. They also provide valuable information in clinical trials, such as individual biological characteristics and disease processes. This can aid researchers in the investigation of treatment possibilities and new modalities – all of which can transform clinical practice and potentially improve therapeutical outcomes.
For example, in the treatment of metastatic breast cancer (also known as advanced breast cancer in Europe), biomarkers CA15-3, CA27.29, and/or carcinoembryonic antigen (CEA) are commonly found in the bloodstream of patients. Serum tumor markers can be monitored with blood tumor marker tests, and abnormal levels of these biomarkers can help scientists better understand the disease.
Of course, biomarker testing is typically recommended to be done alongside other monitoring methods, such as biopsies and imaging methods (such as MRI, CT scans, PET scans, X-rays, and bone scans). This is because biomarkers, while helpful, do not provide the full picture when it comes to disease spread and stage. Alongside a tissue biopsy, clinicians can make a definite diagnosis and receive more accurate insights into disease development and progression.
Managing cancer is difficult, scary, and often a lonely process, with little assurance and a lack of information on the disease and its prognosis. Understanding the outlook of advances in cancer management can provide some peace of mind, as patients become familiar with their disease and the processes they will be required to undergo to manage it.
As the status of biomarker research evolves and biomarker usage becomes widespread, healthcare providers and scientists recognize their vital involvement in driving personalized medicine and the immense potential they hold in creating effective patient care strategies. There is much to be researched and further investigated, but the future of biomarker testing is bright.
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