Screening for Cancer Through Blood Samples
Each year, millions of individuals are affected by cancer, a disease in which cells uncontrollably divide and destroy surrounding tissue. A major factor allowing cancer to be so widespread is the late diagnosis of cancer. Though the most effective way to combat cancer is through early intervention and detection, finding an efficient and reproducible method has been a challenge. However, researchers at Johns Hopkins University School of Medicine in partnership with other hospitals and universities have developed a new method that is currently one of the most powerful and selective ways of screening patients for cancer. Known as targeted error correction sequencing (TEC-Seq), this noninvasive liquid biopsy method detects tumor-derived genes in blood samples through deep sequencing.
The problems in previous cancer screening methods were that protein biomarkers used to detect cancer were found in both healthy individuals and individuals with cancer. Furthermore, most methods could only detect a specific kind of cancer. In a more direct and sensitive approach, the TEC-seq method aims to bypass these problems by detecting circulating tumor deoxyribonucleic acid (ctDNA), tumor-derived pieces of DNA in the bloodstream, in the blood samples of patients in the early stages of cancer without researchers knowing beforehand what genes were altered in their tumors. This method further takes into account the natural differences in DNA due to blood cell multiplication and genetic variations between individuals.
The problems in previous cancer screening methods were that protein biomarkers used to detect cancer were found in both healthy individuals and individuals with cancer. Furthermore, most methods could only detect a specific kind of cancer. In a more direct and sensitive approach, the TEC-seq method aims to bypass these problems by detecting circulating tumor deoxyribonucleic acid (ctDNA), tumor-derived pieces of DNA in the bloodstream, in the blood samples of patients in the early stages of cancer without researchers knowing beforehand what genes were altered in their tumors. This method further takes into account the natural differences in DNA due to blood cell multiplication and genetic variations between individuals.
Image Source: PublicDomainPictures
Researchers examined the effectiveness of the TEC-seq method by analyzing the blood samples of 238 individuals. Of these 238 individuals, 44 were healthy (no history of cancer and negative screening results) and 194 patients were diagnosed with colorectal, lung, ovarian, or breast cancer at various stages. After taking into account differences in DNA due to blood cell multiplication and genetic variations between individuals, researchers were able to identify at least one alteration in the blood samples of 82% of patients that was identical to their tumor samples. No tumor-derived alterations were found in the blood samples of healthy individuals. In total, ctDNA alterations were detected in 62% of Stage I and II individuals, 77% of Stage III and IV individuals, and 67% of Stage I-IV individuals.
From these results, the researchers further predicted that the amounts of ctDNA in an individual may be an indicator of how likely a patient would have cancer again and survive after surgery. To investigate this hypothesis, researchers examined the ctDNA of colorectal cancer patients in relation to disease progression. As the researchers predicted, they found that high amounts of ctDNA correlated with poorer prognosis, shorter progression-free survival (PFS), and overall survival (OS) compared to those with lower amounts of ctDNA.
Though the TEC-seq method can be improved by increasing sensitivity and accuracy, this method is still worth developing on a larger scale. This method has the potential to detect colorectal, ovarian, lung, and breast cancer in their early stages in more than half of cancer patients. Additionally, analyzing ctDNA, as observed from the study of colorectal patients, can facilitate earlier intervention to increase the likelihood of survival and non-recurrence of cancer after surgery. The TEC-seq method combined with early intervention can greatly reduce the current health costs of treating cancer, especially in the later stages, by fighting cancer before it has progressed too far. Therefore, though still in development, the TEC-seq method is currently one of the most powerful ways to fight cancer by allowing for the detection and intervention of early-stage cancers
From these results, the researchers further predicted that the amounts of ctDNA in an individual may be an indicator of how likely a patient would have cancer again and survive after surgery. To investigate this hypothesis, researchers examined the ctDNA of colorectal cancer patients in relation to disease progression. As the researchers predicted, they found that high amounts of ctDNA correlated with poorer prognosis, shorter progression-free survival (PFS), and overall survival (OS) compared to those with lower amounts of ctDNA.
Though the TEC-seq method can be improved by increasing sensitivity and accuracy, this method is still worth developing on a larger scale. This method has the potential to detect colorectal, ovarian, lung, and breast cancer in their early stages in more than half of cancer patients. Additionally, analyzing ctDNA, as observed from the study of colorectal patients, can facilitate earlier intervention to increase the likelihood of survival and non-recurrence of cancer after surgery. The TEC-seq method combined with early intervention can greatly reduce the current health costs of treating cancer, especially in the later stages, by fighting cancer before it has progressed too far. Therefore, though still in development, the TEC-seq method is currently one of the most powerful ways to fight cancer by allowing for the detection and intervention of early-stage cancers
Featured Image Source: U.S. Department of Energy
RELATED ARTICLES
Vertical Divider
|
Vertical Divider
|
Vertical Divider
|