New research provides strong evidence that a common Type-2 diabetes drug prevents cancer promoting substances from stimulating the growth of breast cancer cells. The research was sparked by population studies that associated the Type-2 diabetes drug metformin with a reduced risk of diabetes-associated cancers.
This study adds to a growing body of research that shows that metformin may prevent or slow many types of cancer growth including colon, lung, prostate, liver and pancreatic cancer. Last year, a small human study found patients with precancerous rectal lesions showed significant improvement after one month of treatment with metformin. Another study using mice found that metformin lowered the risk of lung cancer by as much as 70%.
This new study, conducted by Michigan State University and South Korea's Seoul National University focused on the premise that cancers originate from adult human stem cells and that natural and human-made chemicals enhance the growth of breast cancer cells.
Using culture dishes, they grew human breast tumors, or mammospheres, that activated a certain stem cell gene (Oct4A). Then the mammospheres were exposed to two known growth factors that promote tumors -- natural estrogen and certain man-made chemicals.
The researchers found that estrogen and the chemicals caused an increase in the numbers and size of mammospheres. With metformin added, the numbers and size of the mammospheres were dramatically reduced.
Even though each of the chemicals enhanced growth by different means, metformin inhibited their growth in all cases.
This study establishes a causal relationship between metformin and breast cancer cell growth where there had been only an association between the drug and a lower risk of certain cancers. Further research is needed to know the exact mechanism of action but the results are encouraging. It remains to be seen if metformin might be used as a preventive drug and for those who have no signs of existing cancers.
In addition to breast cancer, those with Type-2 diabetes are also at a high risk for liver and pancreatic cancers. Additional research still needs to be done with human cultures to confirm that metformin can reduce the risk of pancreatic and liver cancers in Type-2 diabetics as well.
Additional studies are already being planned to continue to examine the potential for metformin to reduce the risk of many types of cancers in both diabetic and non-diabetic individuals.