A Layman's Perspective on the Role of Metformin in the Treatment of Prostate Cancer

I am neither a doctor nor scientist nor do I have ready access to medical journals. Nor have I ever been accused of being overly academic. When a bona fide research document comes my way I often have difficulty in determining its full scientific value. Accordingly the following information is shared, sketchy though it may be, in the hope that a few others in my situation will be made aware of the potential of Metformin in the treatment of prostate cancer. Another positive outcome would be to trigger responses from individuals who can fill in the blanks.

My initial protocol prescribed by Dr. Myers in 2013 did not include Metformin. In 2014 in conjunction with a few other changes Dr. Myers prescribed a daily dose of Metformin. At the time I described the purpose of this addition as follows: "This drug is a first line treatment for Type II diabetes. It works by suppressing glucose production of the liver. Based on an Internet medical site this drug also "exhibits a strong and consistent antiproliferation action on several cancer cell lines including prostrate cancer cells." This October Dr. Myers quadrupled my prescription Currently my protocol calls for four 500 mg tablets a day, i. e., two each morning and two each evening.

In retrospect I cannot recall an explanation for this rather substantial increase. About the only comment I can recall went something like follows: "Metformin" (pause) "now there is an interesting medical story if ever there was one." As I reflected more on our discussion and mentally chastised myself for not raising a few logical and timely questions, I recalled an Internet audio-visual presentation by Dr. Myers on this topic; a summary of this presentation appears below:

Patients on Metformin:

1.In the treatment of diabetes:

--experienced fewer mortalities from a variety of adult illnesses including heart attacks, strokes and cancers.

--experienced a reduction in diagnoses of all cancers.

2. In the treatment of prostate cancer:

--"Put a lid" on the progression of metastatic prostate cancer in a sizable proportion of patients in a Swiss study.

--(may) reduce the likelihood of developing hormone resistance.

--reduces the development of adverse side effects of hormone therapy.

--prevents the weight gain associated with hormone therapy.

Dr. Myers concluded his presentation with the following prediction (paraphrased):   " I expect Metformin to become a part of any Pca treatment program designed to induce a compete and durable remission."

Addendum January 1, 2015

One of my trusted advisors "Iron Mike" offered the following comments:

"In contrast to Dr. Myers views, however, there was a report just a few months ago based on a meta-analysis of data from nearly 1,000 patients, all of whom had a history of treatment with metformin and all of whom were all newly diagnosed with non-metastatic prostate cancer between April 1, 1998 and December 31, 2009, suggesting no benefit whatsoever from their use of metformin before or after diagnosis with prostate cancer.

Indeed,in that study (see here) a cumulative duration of treatment (before and after diagnosis with prostate cancer) with metformin of ≥ 938 days was actually associated with a roughly threefold increase in risk for prostate cancer-specific mortality.

In all honesty, until we have some data from a large, well-conducted, randomized trial, I think the jury is out on whether metformin has any meaningful clinical benefit in the management of prostate cancer."

When and if I can reconcile the vastly different points of view expressed herein, I will do so.

Addendum January 12, 20i5
Dr. Myers weighed in on the meta-analysis report as follows:

"THAT STUDY IS A POPULATION-BASED STUDY AND AS SUCH PROBABLY NOT WORTH THE PAPER IT IS WRITTEN ON. WE HAVE A PHASE 2 TRIAL SHOWNG A RESPONSE RATE CLOSE TO THAT OF TAXOTERE":
Addendum January 14, 2015
"Iron Mike" responded to Dr. Myers as shown:
"Alas that Swiss Phase II trial was a non-randomized, single arm trial in just 44 patients. As I indicated above, it is "interesting" but hardly "compelling" (in my judgment). Dr. Myers is, of course, entirely entitled to his opinions, but we appear not to be on the same page yet about the potential value of metformin.
My suspicion at this time is that metformin may have value in a particular subset of men with  advanced prostate cancer. The difficulty will be working out how to define and identify that subset."

Addendum January 29, 2015
In a recently released audio-visual Dr. Myers discusses the use of metformin to slow or prevent the return of prostate cancer after complete remission has been achieved by more aggressive forms of treatment. Avodart is  now routinely used for this purpose. Dr.Myers indicates several studies demonstrate metformin shows great promise