Tom,
Sugar provides fuel for all types of the body's cells, including cancer cells. Our bodies need glucose, the broken down form of sugar, for energy. Even if you cut out every bit of sugar from your diet, your body will make sugar from other sources, like protein and fat. This is a confusing subject, but one of my esteemed colleagues has put together a well referenced article on the subject at this link.
http://www.caring4cancer.com/go/cancer/nutrition/questions/s
Bottom line: Carbohydrates and sugars are OK in moderation. Attention should instead be paid to avoiding insulin spikes.
I hope this helps.