A team of scientists from the Johns Hopkins Kimmel Cancer Center has developed a non-invasive way to detect cancer-related DNA in the blood of patients. This method is not only a more convenient way of detecting certain cancers, but the blood test can also detect the disease in its early stages.
'Liquid Biopsy'
Often, medical practitioners order biopsies to determine the presence of cancer in a patient. The process is quite invasive as it involves taking tissue samples from the body part in question to examine it thoroughly. While it is widely used in oncology, it does come with risks which include bleeding and infection.
The new, non-invasive test is called a "liquid biopsy" as it entails drawing blood from a patient. It works by detecting cancer-derived DNA in the blood of patients while also lessening the risks for false positive results.
Cancer vs Non-Cancer Mutations
A major challenge to the scientists involved in the study was to differentiate the genetic mutations that are related to cancer and those that are not. For instance, in the process of blood cell division, there is a possibility of cell mutation, which in some cases, sets up the condition for leukemia. However, these mutations are more often unrelated to cancer.
Further, the team also wanted to rule out "germline" mutations, or ones that occur normally among individuals.
Cancer-Derived Mutations
To develop the new test, the scientists first identified 55 genes which are often related to cancer-related mutations. They also included three additional genes which have previously been linked to mutations among healthy individuals.
The team then collected blood samples from 200 cancer patients with ovarian, lung, breast, and colorectal cancer, as well as samples from 44 healthy individuals.
Using TEC-Seq, or targeted error correction sequencing approach, the team was able to detect early-stage cancers — stages I and II — in 68, 59, 59, and 71 percent of ovarian, breast, lung, and colorectal cancer patients respectively. What's more, they did not detect the cancer-derived mutations in any of the 44 healthy individuals.
Promise For The Future
While the results of the study are promising with regards to early cancer detection, researchers believe that there are two things that still need to be developed. First, further studies using larger populations, and second, such tests could be costly.
Still, a development in cancer diagnostics such as this could really help in detecting cancer in its early stages, thereby reducing morbidity and mortality rates. Further, it could also be an important tool in reducing the number of false positive cancer results which often lead to over-treatments and over-testing.
Results of the study are published in the journal Science Translational Medicine.
