Besides keratin 19, recently described as CTC marker for breast cancer and other epithelial malignancies (Alix‐Panabieres & Pantel, 2014a), viable CTC‐ITB‐01 cells actively secreted vascular endothelial growth factor (VEGF) known to induce tumor angiogenesis in patients with cancer (Saharinen et al, 2011) (Appendix Fig S2). Here, VEGFA is linked to breast cancer.