It’s an incredible discovery. Researchers in the John Hopkins University in Baltimore (US) have invented a simple blood test that can detect early stage cancer. The diagnosis is reliable in 70% of cases. So how does the test work, and when will it be available?
How does the test work?
It this test becomes a routine test during medical visits in the near future, it would help diagnose any type of cancer before symptoms appear and thus increase chances of recovery.
The blood test developed by the researchers in the American university can detect tumours at a very early stage, by simply examining the DNA and the cancer proteins in the blood. In fact, cancer results from DNA mutations, which is why it is possible to detect it before the growths form.
Called CancerSEEK, this new test produced a positive results in around 70% of people affected by cancer. The study sample included over 1,000 patients affected by one of eight types of common cancers.
The prestigious journal Science published these results on the 18th January 2018. The team of researchers estimate the cost of CancerSEEK at less than 500 dollars per sample, a price which fits in with the range of other diagnostic tests for cancer such as colonscopy.
In the majority of cases in adults, you need to wait 20 or 30 years for cancer cells to spread throughout the body and form metastases (secondary cancerous tumours in a different area from the original site of the cancer). However, once the metastatic stage is reached, the chances of recovery are reduced and surgery is more risky. The main objective of this new diagnostic test is to detect cancer before it reaches this stage, in order to increase the chances of the treatment working.
The test can locate the organ where the cancer started
In creating CancerSEEK, the researchers focused their test on detecting 16 genes often muted in various cancers and 8 proteins characteristic of specific types of cancer. Thanks to protein markers, the results allowed them to “not only identify the presence of relatively early stage cancers but also to identify the organ where the cancer originated”, according to the team. They are already planning to market this universal cancer screening test.
During the study, cancer was detected in 33 to 98% of cases depending on the type of cancer, with an average of 70%. The sample of participants was made up of 1,005 stage I to stage III non-metastatic cancer patients (patients whose cancers have not spread from the original location). The patients presented with ovarian cancer, liver cancer, stomach cancer, pancreatic cancer, oesophageal cancer, colo-rectal cancer, lung cancer and breast cancer, which count for 60% of cancer related deaths in the United States.
Of the eight types of cancers studied, five types do not currently have screening tests (ovarian, liver, stomach, pancreatic and oesophageal cancers), but the CancerSEEK test can detect the presence of these cancers in 69 to 98% of cases.
Little room for diagnostic error
The CancerSEEK test is very reliable, and it produced only 1% of “false positives” (people who tested positive despite being healthy). In total, 7 healthy participants of 812 tested positive.
However, the 1,005 patients examined were already presenting with symptoms of cancer, and were thus already at a relatively advanced stage. The test detected 43% of very early stage cancers -at stage I -which is a good result for a first test, as further versions that follow could be improved upon. After two positive tests, the next step for the patient is to arrange for scans to try and find the tumour.