Biomarkers for Cancer: An Overview

Cancer is a deadly disease associated with a high mortality rate. Most forms of cancers have a high recurrence rate and can cause significant morbidity in a patient’s life. Screening and early diagnosis of cancer are vital for prompt treatment onset and good prognosis. Cancer biomarkers are crucial for the timely detection of malignant disease. Biomarkers for cancer are also instrumental in monitoring treatment progression in cancer patients. This article will discuss the currently used biomarkers for cancer detection in clinical practice and provide an overview of the efficacy of suPAR as a biomarker for cancer.

Which Biomarkers Exist for Cancer?

Cancer biomarkers can be grouped into two categories based on their usage¹ :

• Predictive biomarkers: These biomarkers predict response to specific therapeutic interventions and assess the effectiveness of a particular cancer therapy.
• Prognostic biomarkers: These biomarkers aim to inform the physicians the risk of clinical outcomes of a cancerous condition, such as disease recurrence or progression.

The currently available cancer biomarkers and their clinical uses are listed as follows² :

• Prostate-specific antigen (PSA): Used for screening, diagnosis and monitoring of prostate cancer and benign prostate hyperplasia (BPH).
• Carbohydrate antigen 125 (CA125): Used for diagnosis and prognosis of ovarian cancer. This biomarker is also used to detect recurrence rate and for therapeutic management of ovarian cancer.
• Carcinoembryonic antigen (CEA): Used for screening hepatic (liver) metastases. It is also used for assessing prognosis, detecting recurrence rate, and monitoring therapy of colorectal cancer.
• Carbohydrate antigen 15-3 (CA 15-3): Used to monitor breast cancer therapy.
• Estrogen, progesterone receptors (ER and PgR): Used for stratification and selection of breast cancer patients for endocrine therapy.
• HER2: Used to monitor trastuzumab therapy in breast cancer patients.
• Carbohydrate antigen 27.29 (CA 27.29): Used for monitoring breast cancer therapy.
• Human chorionic gonadotrophin-B (HCG-B): Used for diagnosis, staging, recurrence detection, and monitoring therapy of testicular cancer.
• Alfa-fetoprotein: Used for diagnosis, recurrence detection, and monitoring therapy of hepatocellular carcinoma (liver cancer).
• Calcitonin: Used for diagnosis and monitoring therapy of medullary carcinoma of the thyroid gland.
• Thyroglobulin: Used for monitoring thyroid cancer treatment.
• CA 19-9: Used for monitoring therapy of pancreatic cancer.
• Nuclear matrix protein 22 (NMP-22): Used for screening, monitoring and determining prognosis of bladder cancer.
• Prostate cancer antigen 3 (PCA3): Used for prognostic purposes in prostate cancer patients.

suPAR as a Biomarker for Cancer

In cancerous diseases, suPAR is expressed on the cancer cells. Multiple studies support the strong association between suPAR and different types of cancer. The important research studies are listed as follows:

• In 2015, a study published in Liver International reported that the specificity and negative predictive value of suPAR make it a potential screening tool for the early detection of hepatocellular carcinoma in patients with chronic liver disorders³.

• A study published in Clin Appl Thromb Hemost in 2003 reported significantly elevated serum suPAR levels in association with advanced small-cell lung cancer⁴.

• In 2014, a study conducted on patients with advanced alimentary tract carcinoma reported high levels of suPAR. The study also found that highest suPAR levels can be detected in advanced disease with remote metastases⁵ .

• A study conducted in 2015 and published in the International Journal of Cancer reported high levels of suPAR in metastatic colorectal cancer patients. The study also found that circulating suPAR levels would be higher in patients who do not respond to cetuximab treatment than in patients who respond. This finding supports the predictive value of suPAR in oncology⁶ .

• Elevated suPAR levels are associated with increased risk of incident respiratory cancer. These findings published in the Cancer Epidemiology, Biomarkers & Prevention in 2011 also reported that suPAR could be used for evaluation in cancer risk algorithms⁷.

• As per a 2019 study published in Journal of Clinical Oncology, circulating suPAR represents a novel prognostic marker in pancreatic adenocarcinoma patients undergoing tumor resection⁸ .