Link T, Passek S, Wimberger P, et al. - Given that up to 40% of cases of ovarian cancer show calretinin (CRT; a calcium-binding protein that controls intracellular calcium signaling) expressed in ovarian cancer tissues, researchers investigated whether it can serve as a clinically useful blood based-biomarker for ovarian cancer. They analyzed 515 serum samples from healthy controls (n = 116) and ovarian cancer patients (n = 134) (thereof 86% with FIGO III/IV). Ovarian cancer patients vs healthy controls exhibited significantly increased serum CRT (sCRT) level. sCRT level was mostly independent from CA125 and allowed accurate differentiation between cases and controls. In addition to predicting suboptimal debulking, higher sCRT level at primary diagnosis was found to be related to advanced FIGO-stage and increased volume of ascites. Poor PFS and OS were independently predicted by sCRT levels at primary diagnosis and its dynamics in the course of chemotherapy. Platinum-resistance was independently predicted by both sCRT at primary diagnosis or a relative sCRT rise in the time interval between operation and the onset of chemotherapy. For the first time ever, sCRT was suggested as a liquid biopsy marker that can enable independent prediction of platinum-resistance and prognosis.