GDF15 and breast carcinoma: One study comparing GDF‐15 levels of pancreatic cancer patients with several other tumour entities similarly revealed lower concentrations of GDF‐15 for breast cancer patients,25 albeit in vitro data suggest a participation of GDF‐15 in malignant progression of breast cancer cell lines.26 Importantly, we found the highest crude hazard ratios for GDF‐15 in breast cancer patients in our analysis.