Potential of metformin in management of recurrent/progressive prostate cancer

A newly published, retrospective, epidemiological study has looked at the potential role of metformin the the management of prostate cancer in > 350 men already diagnosed and being treated for diabetes in the Shared Equal Access Regional Cancer Hospital (SEARCH) database.

Allott et al. explored whether they could find associations between pre-surgical use of metformin, drug  dose, duration of use, and biochemical recurrence in prostate cancer patients with diabetes who had also undergone a radical prostatectomy.

Here are the basic findings of this study:

  • 156/371 diabetic, male patients (42 percent) were already using metformin prior to their radical prostatectomy
  • Use of metformin prior to surgery
    • Was associated with more recent time of surgery (P < 0.0001)
    • Was not associated with any identifiable clinical or pathological characteristics of the patients
  • After adjustment for year of surgery and for specific clinical and pathological findings, there were no evident associations between time to biochemical recurrence and
    • Metformin use (hazard ratio [HR] = 0.93)
    • High metformin dose (HR = 0.96)
    • Duration of metformin use (HR = 1.00)
  • 14/371 patients (3.8 percent) went on to develop castration-resistant prostate cancer (CRPC).
    • 10 of these 14 patients (2.7 percent overall) had distant metastases.
    • 8 of the 14 patients (2.2 percent overall) actually died of prostate cancer
  • In comparing high metformin use to non-use of metformin, high metformin use  was associated with
    • Increased risk for CRPC (hazard ratio [HR] = 5.1)
    • Increased risk for metastasis (HR = 4.8)
    • Increased risk for prostate cancer-specific mortality (HR = 5.0)

The authors conclude that

  • Metformin use, dose of metformin, and/or duration of metformin use was not associated with risk for biochemical recurrence  in this cohort of patients.
  • The concept that higher metformin dose might be associated with increased risk for CRPC, increased risk for metastases, and/or increased risk for prostate cancer-specific mortality id worthy of testing in large prospective studies with longer follow-up.

As regular readers will already have noted, at least one prospective trial is currently in development to test the latter concept.

One Response

  1. This is a shame because some practicing internists think that metformin is the only oral hypoglycemic agent that actually works to control blood sugar.

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