According to an article in the December 2013 issue of the Journal of Clinical Investigation, a dramatic increase in the uptake of sugar by a cell could be a cause for its becoming cancerous. The article reported that cancer cells have 400 times the ability to transport sugar into themselves.
We know that cancer cells cannot make energy as well as normal cells because their mitochondria (energy producing factories within the cell's cytoplasm) are defective. This leaves cancer cells dependent on metabolizing sugar for energy production.