Fructose — which is added to thousands of US food and drinks — was found to speed up the growth of certain kinds of skin, breast and cervical tumors. 

The study showed this type of sugar gets converted by the liver into components that tumors need to build new cells and grow. 

The more quickly a tumor grows, the more aggressive the cancer may become - able to take over a person's body before they can fight back. 

Added fructose is sugar that is extracted from sources like corn and added to processed foods, most commonly in the form of high fructose corn syrup.

Some early studies have suggested that eating more of these processed sugars might not just accelerate cancer growth, but could also be a cause of some kinds of cancer. 

Added fructose is different from fruit fructose, a natural sugar found in fruits that is typically accompanied by fiber and other nutrients that slow down its absorption into the blood.

In the US, manufacturers are generally allowed to add fructose to foods without limitation, which means its found in high amounts in many different processed foods. 

Similarly developed nations have issued caps on the additive — the EU only permits a fraction of the sugar in its processed foods. 

This creates a food system in the US where fructose, and high fructose corn syrup, is found in sweetened items, like soda, fruit juice and yogurt, as well in unexpected items, like pasta sauce, salad dressing.

Study author Gary Patti, a professor of chemistry, genetics and medicine at Washington University in St Louis said: 'One take-home message from this current study is that if you are unfortunate enough to have cancer, then you probably want to think about avoiding fructose. Sadly, that is easier said than done.'

That's because there is fructose added to many of the foods that Americans reach for every day. 

The average American consumes about 17 teaspoons of added sugar per day - which is more than double the amount that the American Heart Association recommends.