Study into new blood test able to detect cancer

The Dana-Farber Cancer Institute in the United States will soon launch a clinical study to use a blood test to detect cancer in at risk patients. The previous study, with almost 7,000 participants, was able to detect more than 50 types of cancer with a relatively high degree of accuracy. The test could play a key role in the early detection of cancer, which is very important for successful treatment. 

How does the test work? 
The DNA of our cells contains chemical units called methyl groups. These are attached to certain parts of the DNA and help control whether genes are active or inactive. In cancer cells, the placement of the methyl groups, or methylation pattern, is often remarkably different from that of normal cells. When tumour cells die, their DNA with the methyl groups attached to it comes into the blood, where it can be analysed by the new test. 

Results of the previous study
If a diagnosis was made, it was correct in 99,3 % of the cases and false positive in 0,7 % of the cases. If the cancer was in a more advanced stage, it was easier to make the diagnosis. Below you will find the number of cancers that the blood test was able to detect, ranked according to the different stages:
- Stage I: 18 %
- Stage II: 43 % 
- Stage III: 81 %
- Stage IV: 93 %

In addition, if the cancer had been detected, the test was able to correctly identify the organ or tissue in which the cancer had originated in more than 90 % of cases. The blood test is a promising technique, but many questions still need to be answered before it will be used on a large scale.