A new blood test can double the number of cancer cases detected before symptoms develop, when combined with existing screening programmes.
The study is the first to exclusively screen healthy individuals who had no known cancer at the time of enrolment. The results enabled physicians to provide earlier, guided intervention, which is thought will increase the chances of survival.
David Daly, chief executive officer of Thrive Earlier Detection Corps – the company developing the test – expressed hope that 'in the future, most cancers can be identified through earlier detection when there is the greatest opportunity for cure'.
The study, published in Science and conducted by Johns Hopkins University in Maryland and US healthcare company Geisinger, enrolled over 10,000 women with no prior history of cancer. The test screened 16 genes and nine proteins known to be involved in multiple cancers. If positive, a secondary blood-test was performed, and if concerning results persisted, full-body imaging was undertaken. If a tumour was located, women were referred to specialists for treatment.
During the study, 96 women developed cancer. Twenty-six of these cases were first caught by the test with 17 being early-stage. Another 24 cases were found by traditional screenings, whilst 46 were detected from symptoms.
These results suggest that, when used alone, the test missed almost 73 percent of cancers, raising questions on its sensitivity. However, of the ten types of cancer the test identified, seven have no approved screening test.
'Such a test should be employed in a complementary way to increase cancer detection rates' the authors wrote, and should not replace existing screening programmes.
The number of false positives also raised concerns: 101 of the women with positive blood results turned out not to have cancer. False positives can cause anxiety and needless costly procedures. However, a 12-month follow-up survey reported only one of the false-positive tested women regretted partaking in the study.
Ovarian cancer specialist Professor David Huntsman of the University of British Columbia – who was not involved in the study – stressed that more data indicating an overall survival benefit are needed before such tests could be approved for widespread use.