Diabetes Drug Improves Outcomes for Cancer Patients

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A new study published online in The Oncologist journal shows that cancer patients with concurrent type 2 diabetes treated with metformin have a greater overall survival rate compared with patients taking other glucose-lowering medications. A team of researchers led by Ming Yin, MD, at Geisinger Medical Center in Danville, PA, performed a meta-analysis to evaluate the association of metformin treatment and both overall and cancer-specific survival.

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Metformin can make a substantial difference in outcome for diabetic cancer patients.

Over the last four years, a number of studies have compared the survival outcomes of diabetic cancer patients treated with metformin with those treated with other drugs; however, the results from individual studies of different cancers were inconsistent. Yin and colleagues identified 20 studies of patients with cancer and concurrent diabetes, which also reported survival data according to metformin treatment. They then employed statistical methods commonly used in meta-analyses to adjust for confounding variables, heterogeneity between studies, and publication bias.

There were a cumulative 13,008 participants in the studies, slightly less than half of whom underwent metformin treatment either alone or in combination with other glucose-lowering therapies. The remainder of the patients received only non-metformin therapies to control their diabetes. The analysis demonstrated that metformin treatment was associated with a significantly lowered risk of death (approximately 34 percent) compared with no metformin treatment. Even after excluding the largest study from the meta-analysis, which accounted for nearly 40% of the total participants, the results did not change significantly. In fact, a sensitivity analysis, which involved excluding one study at a time from the analysis, revealed that no single study influenced the overall conclusion: patients treated with metformin consistently fared better.

The authors also evaluated the differences among the individual cancer types. Using one analysis, a fixed-effect model, they found that a significant metformin-associated reduction in risk of death was seen in breast, prostate, pancreatic, and colorectal cancer but not in lung cancer. Using the more conservative random-effects model, significantly lower risk of death was observed for pancreatic and colorectal cancer, but only a trend toward lower risk was observed for breast, prostate, and lung cancer. When stratifying by global region, metformin-treated patients in both Eastern and Western countries independently saw improved survival compared with their non-metformin-treated counterparts.

“Metformin can make a substantial difference in outcome for diabetic cancer patients,” said Dr. Yin, lead author of the study. While there are several limitations in such an analysis, the results of this one remain compelling: barring any contraindications, metformin may be the drug of choice for patients with cancer who also have type 2 diabetes.

Bruce Chabner, MD, Editor-in-Chief of The Oncologist, noted, “While there is little doubt that type 2 diabetes increases the incidence of various solid tumors, the added contribution of specific insulin medications now seems unlikely. Dr. Yin’s meta-analysis addresses a more relevant and informative topic, the growing evidence for an antitumor effect of metformin, a common oral medication for control of type 2 diabetes.”

The study will appear in the December issue of The Oncologist, along with a commentary by Carlo La Vecchia, MD, and Cristina Bosetti, PhD, “Metformin: Are Potential Benefits on Cancer Risk Extended to Cancer Survival?” which critically examines the evidence of the impact of metformin on cancer risk and prognosis.

Dr. Chabner explained, “As indicated in Dr. La Vecchia’s commentary accompanying the article, we still have an incomplete understanding of the biology behind its apparent beneficial effects on cancer survival, but this is an important lead for the cancer research community, and for patients. How broadly metformin could be applied in clinical practice remains to be determined.”


The full article, titled “Metformin Is Associated with Survival Benefit in Cancer Patients with Concurrent Type 2 Diabetes: A Systemic Review and Meta-analyses,” can be accessed at http://www.TheOncologist.com.

About The Oncologist
Established by oncologists to help physicians better manage their practices in an ever-changing environment, The Oncologist® is the official journal of the Society for Translational Oncology (STO). Now in its 18th year, this internationally peer-reviewed journal focuses on clear and concise interpretation addressing the multimodality diagnosis, treatment, and quality of life of the cancer patient. Each issue is meant to impact the practice of oncology and to facilitate significant communication in the introduction of new medical treatments and technologies. For more information, visit http://www.TheOncologist.com.

About AlphaMed Press: Established in 1983, AlphaMed Press, with offices in Durham, NC, San Francisco, CA, and Belfast, Northern Ireland, publishes three internationally renowned peer-reviewed journals with globally recognized editorial boards dedicated to advancing knowledge and education in their focused disciplines. STEM CELLS® (http://www.StemCells.com), which celebrated its 31st year in 2013, is the world's first journal devoted to this fast paced field of research. THE ONCOLOGIST® (http://www.TheOncologist.com), entering its 18th year, is devoted to community and hospital-based oncologists and physicians entrusted with cancer patient care. STEM CELLS TRANSLATIONAL MEDICINE® (http://www.StemCellsTM.com), in its second year, is dedicated to significantly advancing the clinical utilization of stem cell molecular and cellular biology. By bridging stem cell research and clinical trials, SCTM will help move applications of these critical investigations closer to accepted best practices.

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Sharon Lee
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