Scientists at John Hopkins University have developed a new blood test that could be used to detect eight different types of cancer, according to a new study published in the journal Science.
The test, called CancerSEEK, works by identifying various mutations in DNA and proteins in the blood that have been released by tumour cells. In a trial of 1,005 patients, the test was able to correctly identify different cancers at varying frequencies – it was able to detect 98% of all ovarian cancers, however only 33% of breast cancers were recognised.
Dr Kotryna Temcinaite, Senior Research Communications Officer at Breast Cancer Now, said:
“Liquid biopsies represent a really promising area of research that we hope will help us begin to outsmart breast cancer. The idea that one test could be used to detect multiple types of cancer is exciting, but much larger studies are needed to refine and validate this test before it could reach patients in the clinic.
“While the test showed a high sensitivity in identifying number of cancers, it was unfortunately not quite as effective in breast cancer, with only 33% of breast cancer patients receiving a positive result. CancerSEEK was also less able to identify cancers at stage one – the stage at which the disease can be treated most effectively – compared to more advanced cancer stages. In addition, when it was tested in healthy people, almost 1% received a false cancer result, which would need to be addressed as it is developed further.
"While this test is not yet at a stage where it could replace existing detection methods, we very much look forward to further studies to help realise the potential of these liquid biopsies in detecting cancers earlier and helping guide more personalised treatment for patients.”
Professor Nicholas Turner, Professor of Molecular Oncology at The Institute of Cancer Research, London, and Consultant Medical Oncologist at The Royal Marsden NHS Foundation Trust, said:
“This paper is a step along the way to a possible blood test to screen for cancer, and the data presented is convincing from a technical perspective on the blood test. Potentially we can use a blood test like this to screen for undiagnosed cancers in asymptomatic people, and identify cancers at a point where they are more curable.
“However, the study does not support use of the blood test outside research studies, as it has not shown yet whether the blood test has the characteristics required for population screening, nor whether the blood test will improve outcome. There was a 1% “false positive” rate with the blood test. Although it is unknown if these were really false positives, perhaps those people had undiagnosed cancer, a false positive rate of 1% could be quite a concern for population screening. There could be a lot of people who are told they have cancer, who may not have it. We can only learn about how much this is, or is not, a problem through larger studies. Much larger studies will also be needed to address whether using these blood tests can help improve survival rates.
“We need larger population studies to assess blood tests like this, and it is important that we wait for the results of these studies before people consider having the tests.”