Better Cancer Tracking
Physicians could monitor cancer by screening for tumor DNA
Source: “Development of Personalized Tumor Biomarkers Using Massively Parallel Sequencing”
Victor Velculescu et al.
Science Translational Medicine 2: 20ra14
Results: Researchers from Johns Hopkins University analyzed the DNA of tumors in patients with breast and bowel cancer and found regions of abnormal, rearranged DNA that served as unique biomarkers of each patient’s disease. They then measured levels of cancer-specific DNA in one patient before and after treatment. The ratio of cancer DNA to normal DNA in blood samples dropped dramatically after treatment, but the marker was still detectable, suggesting that the patient should be monitored more closely for possible recurrence of the disease.
Why it matters: Cancer arises when a number of genetic alterations in cells allow them to grow uncontrollably. Tracking those alterations in a patient’s cancer DNA could provide a new way of detecting small tumors or stray cancer cells that linger after treatment. Scientists say the DNA changes detected in the study will prove much more accurate than existing biomarkers such as the prostate-specific antigen (PSA) associated with prostate cancer, which may yield false positives because even healthy cells can produce the protein.
Methods: Researchers compared the genome sequence of patients’ healthy DNA and DNA isolated from tumor tissue. After isolating unique tumor signatures, they developed a test that uses DNA amplification to measure the amount of tumor DNA and normal DNA in blood.
Next steps: To determine how the technology can be most useful in medicine, researchers will use it to analyze different tumor types as well as different stages of tumor progression. They are also working on automating the technique and reducing its cost.