They also seem to break sugar down faster. Cancer's mechanism of quickly and efficiently metabolizing sugar is known as the Warburg effect.
In fact, we've know about the Warburg since the 1920's when Otto Warburg and colleagues observed tumors taking up enormous amounts of glucose compared to what was seen in the surrounding tissue. Additionally, glucose was fermented to produce lactate even in the presence of oxygen, thus the term aerobic glycolysis.
Scientists have long pondered whether this phenomenon is related to how aggressively tumors grow and how cancer cells ferment sugar rather than using the normal mechanisms that cells use to produce energy. It is this fermentation process that has now been positively linked to continually encouraging tumor growth.