There has been some very promising work on mice using 3-bromopyruvate, which interferes with glycosis in liver cancer, and this article I just found on the internet from the May 2006 edition of Science Magazine mentions a few others that interfere with the energy dynamics in cancer cells. These drugs are at various stages of development, including some already in clinical trials. At one point it quotes two scientists who say that glycosis seems to be a factor in the survival of tumors rather than the origins of tumors. Unfortunately, it also makes clear that not all cancers are glycolytic, only about 60% to 90%, so won't cure all cancer patients, even if it works really well.
http://www.usuhs.mil/alumni/energydereg.pdf