Table 1.
Role of metformin in cancer therapy and chemoprevention.
| Study | Study Types | Inclusion | Results |
|---|---|---|---|
| Franciosi, M 2013 PLoS One |
Meta analysis 41 observational 12 RCT |
Observational studies which examined association between metformin exposure and cancer. RCTs which compared metformin and other hypoglycaemic agents |
Observational studies, metformin associated with: Decreased risk of death (6 studies, OR 0.65, 95% CI 0.53–0.80) Decreased all malignancies (18 studies, OR 0.73, 95% CI 0.61–0.88) Decreased liver cancer (8 studies, OR 0.34 95% CI 0.19–0.60) Decreased colorectal cancer (12 studies, OR 0.83, 95% CI 0.74–0.92) Decreased pancreas cancer (9 studies, OR 0.56, 95% CI 0.36–0.86) Decreased stomach cancer (2 studies, OR 0.83, 95% CI 0.76–0.91) Decrased esophageal cancer (2 studies OR 0.90 95% CI 0.83–0.98) In RCTs: No significant effect of metformin on death or malignancies |
| Thakkar, B 2013 Metabolism |
Meta analysis 13 case contro l9 cohort 2 RCTs |
Studies that assess metformin and/or sulfonylurea effects on cancer risk in diabetic patients | In observational studies, metformin use was associated with reduced risk of developing cancer: Cohort studies (RR 0.70, 95% CI 0.67–0.73) Case-control studies (OR 0.90 95% CI 0.84–0.98) In RCTs: No effect on developing cancer (RR 1.01 95% CI 0.81–1.26) |
| Stevens RJ 2012 Diabetologia |
Meta analysis 13 RCTs |
RCTs which compared metformin to another diabetic treatment or placebo/usual care, with minimum 500 participants and 1 year follow-up | In RCTs looking at cancer outcomes (11 studies): RR 1.02 (95% CI 0.82–1.26) (11 studies) In RCTs looking at all-cause mortality (13 studies): RR 0.94 (95% CI 0.79–1.12) |
| Soranna D., 2012 Oncologist | Meta analysis 17 observational |
Observational studies of diabetic patients treated with metformin and/or sulfonylurea where risk of all cancers and specific cancer mortality was investigated | Metformin associated with decreased RR of: All cancers (RR 0.61, 95% CI 0.54–0.70) Colorectal cancer (RR 0.64, 95% CI 0.54–0.76) Pancreatic ca. (RR 0.38, 95% CI 0.14–0.91) Sulfonylurea not associated with reduced RR |
| Noto H., 2012 PLoS ONE |
Meta analysis Cancer Mortality: 4 cohort 2 RCTs Cancer Incidence: 6 cohort 2 case control 2 RCTs |
Studies of diabetic patients taking metformin compared to those not taking metformin | Metformin users compared to non users had: Lower cancer mortality (pooled RR 0.66, 95% CI 0.49–0.88) Lower cancer incidence (pooled RR 0.67, 95% CI 0.53–0.85) Lower colorectal ca. incidence (pooled RR 0.68, 95% CI 0.53–0.88) Lower HCC (pooled RR 0.20, 95% CI 0.07–0.59) Lower lung cancer (pooled RR 0.67, 95% CI 0.45–0.99) |