Fluke or Trend? Metformin vs Cancer Part 4

Thanks for sticking w/me as I've been reviewing some of the current literature on how metformin is safer than  insulin & sulfonylureas when it comes to cancer in diabetics.  Well, do you remember that February 2010 study in Diabetes Care in which the authors demonstrated that diabetics have a greater risk of all-cause, cardiovascular & cancer mortality?

Earliest this year, a retrospective cohort study was published in the February issue of Diabetes Care in which the authors concluded that diabetes was associated with worse cancer mortality but that some diabetes treatments, notably metformin, fared better than others.  In this study, the authors followed 112,408 participants, 8,392 of whom had diabetes, for close to 2 decades and showed that compared to non-diabetics, those with diabetes had a statistically significant 9% greater risk of any cancer death.  Breast cancer deaths were 32% greater while prostate cancer deaths were 19% greater, both compared to non-diabetics.  

But after breaking down by diabetes therapies, sulfonylureas and insulin were both associated w/13% greater cancer mortality while metformin use by itself was associated w/15% less cancer mortality, all relative to non-diabetics.  So our quiver of arrows is now up to at least 5 studies demonstrating benefit of metformin vs cancer.

However, lest you get overly excited about these observational studies, a review of 13 such studies published in this month's Diabetes Care suggests that the supposed benefit can be accounted for time-related biases.  Lest I throw a wet blanket on all the excitement surrounding the potential off-label use of this inexpensive and relatively safe medication, let's not forget the basis of this series of posts was founded upon cellular signaling pathways common to both metformin & exercise, the latter which has also proven beneficial. 

While I can't yet advocate the use of metformin as a prophylactic against cancer, I can certainly urge you to choose to eat healthy foods and to regularly participate in physical activities with a corollary effect of obtaining/maintaining appropriate body weight in order to lower one's risk of developing cancer and improve one's odds of survival.  So don't just sit there, do something!

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