The invention relates to an AMPK activator (such as for instance metformin) for use in preventing metastasis in a patient suffering from a cancer, wherein said patient has a non-mutated p53 gene or lacks a mutant form of the p53 protein. The invention also relates to an AMPK activator for use in improving the survival time of a patient suffering from a cancer, wherein said patient has a non-mutated p53 gene or lacks a mutant form of the p53 protein.