If you want to stop cancer from spreading throughout the body, a good start is to understand exactly how this process takes place. Via the BBC: "primary tumours emit chemical signals. These make the target sites for secondary tumours sticky and direct bone marrow cells to them to secure a foothold for arriving tumour cells. ... Once there, they cluster in groups, forming a support structure which stabilises the malignant cells that arrive later to begin forming a secondary, or metastatic, tumour. ... New York's Cornell University used antibodies to block bone marrow cells' migration in mice, and believe their work could help humans." Cancer is one of the largest obstacles to be overcome on the way to greatly extended healthy life spans - but the rate of progress is promising.