NPPB and hydrops fetalis: The challenge in the upcoming years will be to unravel the shared mechanisms between cancer and HF, and to uncover whether more severe HF (e.g., higher NT-proBNP levels, higher NYHA-classification) is associated with a more aggressive form of malignancy (e.g., higher tumour load, increased spread of metastases) or whether this relationship is unconditional, regardless of HF severity.