A simple ultrasensitive blood test has been reported to be effective for detecting cancer. It holds promise for both monitoring cancer treatment as well as a screening technique. The test could be done at a fraction of the cost—and without radiation exposure—compared to tests such as a CT scan. The study was published online on April 6 in the journal Nature Medicine by researchers at Stanford University.
The test detects circulating tumor DNA (ctDNA), which is a biomarker for the presence o cancer. The authors note that existing ctDNA detection methods do not have sufficient sensitivity or patient coverage to be clinically useful. This, they developed a cancer detection test that used deep sequencing (CAPP-Seq), which is an economical and ultrasensitive method for measuring the amount of ctDNA circulating in the bloodstream. They used the test on patients with non–small-cell lung cancer; it identified cancerous mutations in more than 95% of the tumors.
The test was able to detect ctDNA in 100% of patients with stage II–IV non-small cell lung cancers and in 50% of patients with stage I cancers. It had a specificity of 96% for the type of cancer, meaning that it correctly identified the type of cancer in almost all cases. The researchers found that ctDNA levels significantly correlated with the volume of tumor present in the patient and differentiated between residual disease and treatment-related imaging changes. In addition, the measurement of ctDNA levels facilitated evaluation of response to treatment to a greater degree than radiologic studies such as CT scans.
The researchers also evaluated using the test as a screening procedure that avoided taking a biopsy. They concluded that the CAPP-Seq could be routinely applied clinically to detect and monitor a wide variety of malignancies; thus, facilitating personalized cancer therapy.