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Association between metformin use and mortality after cervical cancer in older women with diabetes

Han K, Pintilie M, Lipscombe LL, Lega IC, Milosevic MF, Fyles AW. Cancer Epidemiol Biomarkers Prev. 2016; 25(3):507-12. Epub 2015 Dec 31.


Background — To examine the association between metformin use and mortality in patients with diabetes and cervical cancer.

Methods — Using Ontario health databases, a retrospective, population-based cohort study was conducted in women with diabetes ≥ age 66 diagnosed with cervical cancer between 1997-2010. The association between metformin exposure and cervical cancer-specific mortality was examined using Fine-Gray regression models, with non-cancer death as a competing risk and cumulative metformin use as a time-varying exposure. The association with overall mortality was examined using Cox regression models.

Results — Among the 181 women with diabetes and cervical cancer, there were 129 deaths, including 61 cervical cancer-specific deaths. The median follow-up was 5.8 years (interquartile range 4.2-9.6 years) for surviving patients. Cumulative dose of metformin after cervical cancer diagnosis was independently associated with a decreased risk of cervical cancer-specific mortality and overall mortality in a dose-dependent fashion (HR 0.79, 95% CI 0.63-0.98; and HR 0.95, 95% CI 0.90-0.996 per each additional 365g of metformin use, respectively). There was no significant association between cumulative use of other anti-diabetic drugs and cervical cancer-specific mortality.

Conclusion — This study suggests an association between cumulative metformin use after cervical cancer diagnosis and lower cervical cancer-specific and overall mortality among older women with diabetes.

Impact — Cumulative dose of metformin use after cervical cancer diagnosis among older women with diabetes may be associated with a significant decrease in mortality. This finding has important implications if validated prospectively, as metformin is inexpensive and can be easily combined with standard treatment for cervical cancer.

Keywords: Cancer Diabetes Women’s health Treatment outcomes

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