BLOBREC – a blood-based test for breast cancer

BLOBREC is a test for distinguishing breast-cancer patients from population-based controls described by Dumeaux et al. Previously, we performed a quality control of the methods and procedures used for developing this test, and our analyses confirmed the results obtained by Dumeaux et al. The aim of these analyses were to study the properties of the BLOBREC test in the years before or after diagnosis, and compare with time of diagnosis. In addition, we looked at effects of parity in controls, and also used a clinical stress study. We had a case-control design with 539 pairs before diagnosis, 59 at and 429 after diagnosis. In the controls taken from the NOWAC postgenome biobank, we found no difference in percentage false positives (%P) between the pre- and postdiagnostic controls (37% and 34% respectively). The %P were similar to the casecontrol study at time of diagnosis; 37%. The %P for cases were except for one year before diagnosis similar to the controls pre- and postdiagnostic. Additionally, we found a weak, non-significant increase in %P for controls with many children. The stress data originated from the “second look” at one single centre in the national screening program for breast cancer. The %P (the per cent of positive tests) were lower both for cases and controls than for the original case-control series. These data were collected under more stringent conditions. Conclusion: the BLOBREC showed higher %P for cases at diagnosis than either before or after, while the %P for controls remained identical. As previous, the %P was higher for metastatic breast cancer. BLOBREC might be improved through a more stringent sampling of both cases and controls.