About 90% of the deaths caused by cancer are due to cancer that has spread (metastasized) to distant locations in the body. New results show that the blood cell fragments called platelets may play an important role in the spread of cancer. Platelets were shown to secrete a protein (TGF-beta) that stimulated cancer cells to begin migrating. Separately, touching platelets directly caused additional changes in the cancer cells. Together, the two activities worked together to make the cancer cells much more likely to move/spread. The results suggest that blocking the platelet:cancer cell interaction could be a good way to prevent the spread of cancer.