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Fructose promotes growth of pancreatic cancer

A new study in the Aug. 1 issue of the peer-reviewed journal Cancer Research says fructose, a monosaccharide that is commonly used in soft drinks and processed foods in the form of high fructose corn syrup in the Western diet can promote growth of pancreatic cancer.

Early studies have already suggested that glucose, which is also present in high fructose corn syrup and can also be derived from carbohydrates like starch, is also able to fuel cancer growth.

A press release by the University of California - Los Angeles says that the current study has demonstrated for the first time that fructose boosts cancer proliferation.

What Dr. Anthony Heaney at UCLA's Jonsson Comprehensive Cancer Center and colleagues found is that fructose activates a key cellular pathway that drives cell division, promoting the growth of cancer cells.

"The bottom line is the modern diet contains a lot of refined sugar including fructose and it's a hidden danger implicated in a lot of modern diseases, such as obesity, diabetes and fatty liver," said Heaney. 

"In this study, we show that cancers can use fructose just as readily as glucose to fuel their growth," Heaney added.

In the study, the researchers compared glucose and fructose to see how pancreatic cancer cells use these two sugars in Petri dishes.

They found the pancreatic cancer cells use fructose in the transketolase-driven non-oxidative pentose phosphate pathway to produce nucleic acids, which are needed for cell division and proliferation.

Heaney suggested that fructose may also be implicated in the growth of other types of cancer.

Although the current study may be the first to demonstrate that fructose boosts risk for pancreatic cancer, early studies have shown that consumption of soft drinks with high fructose corn syrup was linked with higher risk of pancreatic cancer.

Researchers at the University of Minnesota found men and women who consumed two or more soft drinks per week were twice as likely to be diagnosed with pancreatic cancer as those who did not drink the beverage.
For the study, Dr. Mark Pereira and colleagues followed 60,524 men and women in the Singapore Chinese Health Study for 14 years and recorded 140 cases of pancreatic cancer.
Those who drank two or more soft drinks per week were at an 87 percent increased risk of pancreatic cancer compared with those who did not.
Pancreatic cancer is diagnosed in 43,140 people each year in the United States and the disease kills 36,800 annually in the country. No more than 5% of pancreatic cancer patients can survive beyond 5 years after diagnosis.
Pereira said that "The high levels of sugar in soft drinks may be increasing the level of insulin in the body, which we think contributes to pancreatic cancer cell growth."
Interestingly, fruit juice, which contains fructose in many cases, was not associated with pancreatic cancer, according to the researchers.

Still, Pereira's study was not a trial and it does not reveal a causal relationship between consuming soft drinks and elevated pancreatic cancer risk.

It is possible that those who drank beverages with high fructose corn syrup are more likely to follow a lifestyle that is not so healthy and full of other risk factors for pancreatic cancer such as smoking, red meat consumption, which were linked with consumption of soft drink in Singapore, said Susan Mayne at the Yale Cancer Center.

Another study published in the Nov. 2006 issue of American Journal of Clinical Nutrition showed that men and women who added sugar to their food and consumed lots of sugar were at a significantly higher risk for pancreatic cancer compared with those who did not use added sugar.

Dr. Susanna C. Larsson at the Karolinska Instittue in Stockholm and colleagues established the association after studying data from 77,797 men and women aged 45 to 83.

They found those who ate five or more servings of added sugar daily were 69 percent more likely to acquire pancreatic cancer compared with those who never added sugar in their foods and drinks.

Study participants who drank two or more servings of soft drinks per day were 93 percent more likely to have  pancreatic cancer than those who did not use soft drinks. 

And eating sweetened fruit soups or stewed fruit was also linked with a 51 percent higher risk.
Dr. Larsson suspected that use of too much sugar could demand more insulin from the pancreas, which in turn increases the risk of pancreatic cancer.
It has been known for long that people with diabetes or insulin resistance are at higher risk for pancreatic cancer.
Those with diabetes were at a 200 percent increased risk for pancreatic cancer compared with those who did not have the condition, according to Lucio Gullo and colleagues at the Istituto di Clinica Medica e Gastroenterologia in Italy who reported their study on July 14, 1994 in the New England Journal of Medicine.

Some studies imply that high intake of sugar demands high output of insulin, which by itself stimulates cell proliferation and tumor growth and high levels of insulin come with high levels of insulin-like growth factor 1 (IGF-1), which is known to play a key role in promoting cancer cell growth.

It is uncertain whether fructose and glucose promote cancer growth in other pathways. The current study adds to a growing body of evidence that added sugar like high fructose corn syrup promotes cancer development.

By David Liu