Simple Blood Test for Early Cancer Detection Could Soon Be a Reality
Researchers identify cancer biomarkers in patients that could make early, accurate diagnosis possible with a simple blood test
Cancer research has come a long way in the past few decades; however, many patients are diagnosed too late, which decreases their odds of survival. Treatment success and patient survival largely depend on early, accurate detection of tumors. For some cancers, that means diagnosing patients before they start developing symptoms. While that might seem challenging, some cancer-specific biomarkers can be detected long before a tumor becomes metastatic, and if we were to know exactly which ones to look out for, it could potentially revolutionize cancer therapy.
In a groundbreaking new study published in Cell in August 2020, an international team of researchers led by Dr. David Lyden from Weill Cornell Medicine, has identified a list of proteins found in blood plasma and tumor tissues that could be used as cancer biomarkers. They focused on tumor-derived extracellular vesicles and particles (EVPs), which carry cancer-specific proteins in the bloodstream and tumor tissues.
Tumor cells, like any other cell in the human body, communicate with their surroundings through EVPs. In fact, a single drop of blood of a patient with cancer can contain millions of EVPs. Professor Han Sang Kim of Yonsei University College of Medicine in Seoul, Korea, who is one of the lead authors of this study explains, “Although 1 mL of blood contains billions of EVPs, we did not have the biological insight to use this information for detection of cancer. Previously, we used to focus on the primary cancer itself, but ‘messages’ secreted by tumor cells to communicate with adjacent and distant tissues hold importance in cancer detection.”
To begin, the team used 426 human tissue, blood, and lymph samples (including a total of 18 cancer types) to identify several EVP markers that accurately signal the presence of cancer cells in humans. They analyzed the protein profile of EVPs using mass spectrometry and compared the ones that were consistently found in cancer patients with those in healthy subjects. They also identified novel tumor-specific EVPs that were ubiquitous (called “pan-EPV markers") in the blood plasma of cancer patients. These findings indicated that no matter where the primary tumor was located, there were detectable clues in the blood.
The scientists even went a step further: from their established list of EVPs, they found that some proteins were unique to specific types of tumors, such as those typically found in pancreatic and lung cancer. Their analysis shows that these specific biomarkers could be detected in the blood plasma as early as stage I, meaning that the cancer had not yet spread to other areas of the body.
Moreover, using a machine-learning algorithm, the researchers showed that the plasma EVP proteins they had identified could accurately detect 95% of cancers and rule out cancer risk in 90% of tested subjects. With these results, the scientists are confident that EVPs could be used to establish a reliable cancer diagnosis.
Imagine going for your annual check-up and being able to get screened for cancer with a routine blood draw. This study shows that cancer screening in the future could be that simple. “We hope the next step is to develop an EVP blood test kit to use as part of a routine physical exam,” says Prof Kim. "With a blood test, we could possibly diagnose cancer at a patient's yearly physical, prior to symptoms and radiographic evidence,” he concludes.
About the author: Professor Han Sang Kim, of the Yonsei University College of Medicine, Yonsei Cancer Centre, and Weill Cornell Medicine, is one of the lead co-authors of this groundbreaking study.
Updated November 2020
Professor Hyuk-Jae Chang
Professor Sung-Joo Hwang