From ScienceDaily, cancer researchers have established key findings of glucose being used for growth of tumors rather than it's normal use of energy formation (ATP).

Tumors suck up radioactive glucose and allow for detection during imaging exams.

This unique metabolic property of cancer cells has led to the success of PET imaging as a means of cancer detection; because radioactive glucose injected into patients prior to the imaging exam is preferentially taken up by glucose-hungry tumor cells, the areas of high glucose uptake are displayed dramatically on the PET scan...

...The findings are consistent with the idea that tumor cells preferentially use glucose for purposes other than making adenosine triphosphate (ATP), the energy currency used by normal cells. "We suspect that this mechanism evolved to ensure that fetal tissues only use glucose for growth when they are activated by appropriate growth factor receptor protein-tyrosine kinases," adds Cantley. "By re-expressing PKM2, cancer cells acquire the ability to use glucose for anabolic processes.

"The ability to use glucose for anabolic process" spells out growth of a vicious tumor. I find this pretty disturbing and certainly question whether diet is the main fuel behind breast cancer in obese women.

Either way, it's vital to limit your consumption of carbohydrates to protect yourself from cancer.