If you remain unconvinced that sugar causes and fuels cancer, perhaps the findings of a 9-year joint research project will change your mind. In the study, scientists were able to clarify how the Warburg effect – “a phenomenon in which cancer cells rapidly break down sugars” – stimulates the growth of tumors. 
The authors launched the study in 2008 with intent on examining how tumors convert significantly larger amounts of sugar into lactate compared to healthy tissues.
The Warburg effect has been studied extensively, and it has even been used to detect brain tumors. But for the longest time, scientists couldn’t figure out whether the Warburg effect is a symptom of cancer, or the cause of it.
Now they know. 
Professor Johan Thevelein said:
“Our research reveals how the hyperactive sugar consumption of cancerous cells leads to a vicious cycle of continued stimulation of cancer development and growth.
Thus, it is able to explain the correlation between the strength of the Warburg effect and tumor aggressiveness.” 
“This link between sugar and cancer has sweeping consequences. Our results provide a foundation for future research in this domain, which can now be performed with a much more precise and relevant focus.” 
For instance, doctors could potentially tailor diets to the specific needs of cancer patients. 
The bummer news is that many people will develop cancer as a result of eating too much sugar, and that people who already have the disease may be unknowingly making it worse. Did you know that past research suggests that teen girls who eat a poor diet – including a lot of sugar – could be increasing their risk for breast cancer later in life?
It’s worth it to quit sugar, even if cancer isn’t on your radar. You’ll actually have more energy (that’s because sugar spikes lead to energy crashes). You’ll stop craving more sugar, and you’ll lose weight. Your digestive system will work more efficiently, and you’ll have less acne and fewer skin problems.
 Science Daily