MMP9 and cholangiocarcinoma: revealed that alteration of TAMs characterizes early CCA and TAMs are key players in promoting progression and metastasis of CCA.79 TAMs express matrix metalloproteinase‐9 (MMP‐9) to degrade the extracellular matrix that contributes to the metastasis, invasion and low survival rate of CCA.80 By analyzing surgically resected tumour tissues for distribution of TAMs, Atanasov et al.