Cancer is the second most common cause of death, only preceded by cardiovascular diseases. The main reason behind the high mortality rates of cancer is the appearance of metastasis, the dissemination and colonisation of secondary tissues by cells from the primary tumour. In particular, in the case of colorectal cancer (CRC) the survival rates of patients diagnosed, drop drastically if diagnosis happens at later stages when metastasis has occurred. A similar trend can be observed for most of the cancers commonly diagnosed. When metastasis occurs, treatment relies heavily on the use of chemotherapy, even if the original tumour mass is surgically removed, the metastases will still survive. It is thus paramount to find new tools that improve early diagnosis so that detection can occur before the tumour spreads. In this context, the main focus of this thesis has been the understanding and characterisation of CRC metastasis to find new diagnostic markers that can be used in the clinic. We have used isogenic cell lines, that share the same genetic background but have different metastatic capacities, to define the proteome of CRC metastasis in vitro…