Johns Hopkins scientists develop new test for early cancer detection


Johns Hopkins Kimmel Cancer Centre scientists in the US have developed a new blood test that is claimed to detect even tiny amounts of cancer DNA in early stages of the disease.

The test is said to be unique as it can differentiate tumour-shed DNA from other altered DNA that could be mistaken for cancer biomarkers.

Johns Hopkins scientists aimed at developing a highly cancer-specific diagnostic test that can minimise the risk of ‘false positive’ results that might lead to overtesting and over-treatments. 

The test employs a type of genomic sequencing called targeted error correction sequencing that is based on deep sequencing and reads each chemical code in DNA 30,000 times, covering around 80,000 base pairs of DNA.

Johns Hopkins Kimmel Cancer Centre oncology professor Victor Velculescu said: “This study shows that identifying cancer early using DNA changes in the blood is feasible and that our high-accuracy sequencing method is a promising approach to achieve this goal.

"This study shows that identifying cancer early using DNA changes in the blood is feasible and that our high-accuracy sequencing method is a promising approach to achieve this goal."

“The challenge was to develop a blood test that could predict the probable presence of cancer without knowing the genetic mutations present in a person’s tumour.”

The scientists evaluated the DNA-based test on blood and tumour tissue samples of 200 patients with different stages of cancer in the US, Denmark, and the Netherlands.

The test is reported to have accurately detected 86 of 138 participants with relatively early-stage colorectal, breast, lung and ovarian cancers, and did not find any of the cancer-derived mutations in blood samples from 44 healthy individuals.

While the test is yet to be assessed in a larger patient population, it is expected to be useful for high cancer risk individuals such as smokers and those with inherited mutations in breast and ovarian cancer within BRCA1 and BRCA2 genes.