According to a new study in mice, elevated sugar levels typical of Western diets raise the risk for breast cancer tumors and metastasis to the lungs. University of Texas MD Anderson Cancer Center researchers have discovered that fructose boosts the growth of breast tumor, and helps it spread.
Fructose is present in table sugar and high-fructose corn syrup, and is used in high percentage in lot of food items. As per the Dana-Farber Cancer Center, earlier research has linked dietary sugar to many kinds of cancer, and other studies have displayed an association between sugar and inflammation that can result into cancer development. In a press release, Dr. Lorenzo Cohen, a professor of palliative, rehabilitation, and integrative medicine at MD Anderson, said that the present study has investigated the effect of dietary sugar on mammary gland tumor development in a number of mouse models, along with mechanisms that could have involvement in it.
Dr. Cohen added, “We determined that it was specifically fructose, in table sugar and high-fructose corn syrup, ubiquitous within our food system, which was responsible for facilitating lung metastasis and 12-HETE production in breast tumors”. The study was published in the journal Cancer Research. During the study, researchers carried out 4 separate studies randomizing mice to diet groups given one of 4 diets with differing sucrose and fructose levels. Cohen said the study data has suggested that either form of sugar induced 12-LOX and 12-HETE production in breast tumor cells, resulting into tumors growth. But, he has mentioned that further research is required to determine whether sugar has a direct or indirect effect on the growth of tumor. A UPI report informed, “Between 50 and 58 percent of mice on a sucrose-enriched diet developed mammary tumors by the time they were six months old, but just 30 percent of mice on a starch-control diet had measurable tumors at the same age. There were also more lung metastases among mice fed diets higher in fructose or sucrose than in those given a starch-control diet. Previous research has linked dietary sugar to several types of cancer, according to the Dana-Farber Cancer Center, and other studies have shown a connection between sugar and inflammation that can lead to cancer development.”
Research has also pointed to refined sugar as one of the culprits. But this factor is harder to pin down, since “sugar” is a very broadly used term, some sugars are vital nutrients and the body uses a form of sugar called glucose to generate energy. Cohen’s team used mice for their study but say they took many steps to make sure the process was as close as possible to what happens in people. They fed the mice sugar in doses very similar to what Americans eat every day and they used mice that are genetically predisposed to breast cancer in much the same way that many people are. “It seems that fructose is driving this inflammatory process more than glucose,” Cohen said. “It seems from these series of experiments that it really fructose that within the sucrose that is the driver of the tumorigenic process.”
Any sugar helped make the tumors grow faster, but fructose did it significantly more. It’s still not quite clear just how this happens and it’s not clear how the LOX-12 pathway affects cancer, Cohen and colleague Peiying Yang said. But it appears fructose makes LOX-12 more active. There are other reasons to minimize sugar. Other studies show sugar-heavy diets can fuel heart disease, diabetes and Alzheimer’s disease. But cutting sugar can lower blood pressure and blood sugar levels after only a few days, according to a report published in Today magazine.
In the study, researchers investigated the impact of dietary sugar on mammary gland tumor development in multiple mouse models and found that mice who were given diet with sucrose levels comparable to that found in western diets were at an increased risk of tumor growth and metastasis than mice on a non-sugar starch diet. Peiying Yang, Ph.D., assistant professor of Palliative, Rehabilitation, and Integrative Medicine, explained that this is, in part, because of increased expression of 12-LOX and a related fatty acid called 12-HETE. Previous studies have also found a link between dietary sugar intake and breast cancer development.
Lorenzo Cohen, Ph.D., professor of Palliative, Rehabilitation, and Integrative Medicine and co-author of the study explains that through their study they were able to determine that fructose, which is found in table sugar and high-fructose corn syrup, was responsible for facilitating lung metastasis and 12-HETE production in breast tumors. Cohen added that the data suggested that dietary sugar induces 12-LOX signaling to increase risks for breast cancer development and metastasis. Researchers carried out four different studies randomizing mice to different diet groups with each group fed one of four diets. At six months of age, 30 percent of mice on a starch-control diet had measurable tumors, whereas 50 to 58 percent of the mice on sucrose-enriched diets had developed mammary tumors. The study also showed that numbers of lung metastases were significantly higher in mice on a sucrose- or a fructose-enriched diet, versus mice on a starch-control diet.
“This study suggests that dietary sucrose or fructose induced 12-LOX and 12-HETE production in breast tumor cells in vivo,” said Cohen. “This indicates a possible signaling pathway responsible for sugar-promoted tumor growth in mice. How dietary sucrose and fructose induces 12-HETE and whether it has a direct or indirect effect remains in question.”
The study team believes that the mechanism by which dietary sucrose or fructose affects breast tumor growth and metastasis, especially through the 12-LOX pathways, warrants further investigation. Authors of the study advocate moderate sugar consumption for previous studies have already established significant contributory role of sugar in causing obesity, heart disease and cancer worldwide.
