Cancer metabolism has regained substantial research interest over recent years. The focus has been mostly on the primary tumor, while metabolic adjustments during dissemination have been less extensively researched. Deadhesion impairs glucose transport and brings about an ATP deficit that leads to apoptosis. To survive, metastasizing cancer cells need to increase ATP synthesis, which involves mitochondrial activity and is accomplished in part through peroxide signaling. This change in metabolism, associated with cancer spread, is different from the Warburg effect. Therefore it is important to distinguish between the metabolic adjustments in primary tumor cells and those in disseminating tumor cells. In general, it is likely that metabolic responses to environmental cues commonly occur in cell biology.