Table 2.
The effect of metformin on the risk of cancers by type of cancer
| Type of cancer | Authors name | Number of study | Year of study | RR/OR | lower RR/OR | upper RR/OR | Study selection | AMSTAR score |
|---|---|---|---|---|---|---|---|---|
| Hepatocellular/Liver | Siddharth Singh | 10 | Update to Aug 2012 | 0.50 | 0.34 | 0.73 | Removed | --- |
| Hui Zhang | 7 | 1966-2011 | 0.24 | 0.13 | 0.46 | Removed | --- | |
| Ping Wong | 49 | Update to 2011 | 0.31 | 0.19 | 0.49 | Selected | Moderate | |
| Hiroshi Noto | 4 | Until 2011 | 0.20 | 0.07 | 0.59 | Removed | ||
| Shujuan Ma | 19 | Until July 2016 | 0.52 | 0.40 | 0.68 | Selected | Moderate | |
| Zhi-Jiang Zhang | 5 | 1966-2012 | 0.38 | 0.24 | 0.59 | Removed | --- | |
| Monica Franciosi | 8 | 1966-2012 | 0.34 | 0.19 | 0.60 | Removed | --- | |
| New meta-analysis (Ping Wong, Shujuan Ma) | 67 | Up to 2017 | 0.59 | 0.46 | 0.72 | Selected | --- | |
| Ovarian | Shi, J | 6 | Up to August 2018 | 0.76 | 0.62 | 0.93 | Selected | High |
| Wen, Q | 4 | Last search was performed on August 15, 2018 | 0.18 | 0.12 | 0.28 | Removed | --- | |
| Lifeng Li | 5 | Until Jan 2016 | 0.54 | 0.32 | 0.93 | Selected | --- | |
| Pancreatic | Hu, H | 9 | Until September 2016 | 0.61 | 0.55 | 0.67 | Selected | Moderate |
| Zheng Wang | 11 | 1995-2013 | 0.63 | 0.46 | 0.86 | Selected | Moderate | |
| Siddharth Singh | 11 | Update to June 2012 | 0.76 | 0.57 | 1.03 | Removed | --- | |
| Monica Franciosi | 9 | 1966-2012 | 0.56 | 0.36 | 0.86 | Removed | --- | |
| Hiroshi Noto | 6 | Until 2011 | 0.48 | 0.20 | 1.17 | Removed | --- | |
| New meta-analysis (Zheng Wang, Hu, H) | 13 | Up to 2016 | 0.59 | 0.50 | 0.69 | Selected | --- | |
| Head and Neck | Contanza Saka Herran | 13 | 2012-2017 | 0.71 | 0.61 | 0.84 | Selected | Moderate |
| Colorectal adenoma | Deng, M | 13 | Jan 13, 2019 | 0.75 | 0.65 | 0.86 | Selected | Moderate |
| Feifei Liu | 5 | Aug 31, 2016 | 0.80 | 0.71 | 0.90 | Removed | --- | |
| Colorectal | Deng, M | 14 | Jan 13, 2019 | 0.73 | 0.58 | 0.90 | Selected | Moderate |
| Feifei Liu | 12 | Aug 31, 2016 | 0.80 | 0.72 | 0.89 | Removed | --- | |
| Zhihang Nie | 11 | Update to 2014 | 0.75 | 0.66 | 0.86 | Removed | --- | |
| Hiroshi Noto | 6 | Until 2011 | 0.68 | 0.53 | 0.88 | Removed | --- | |
| Monica Franciosi | 12 | 1966-2012 | 0.83 | 0.74 | 0.92 | Removed | --- | |
| Zhi-Jiang Zhang | 5 | 1966-2011 | 0.63 | 0.47 | 0.84 | Removed | --- | |
| Siddharth Singh | 15 | Update to Sep 2012 | 0.89 | 0.81 | 0.99 | Removed | --- | |
| Colon | T. Rokkas | 17 | Until 2015 | 0.79 | 0.69 | 0.91 | Selected | High |
| Andrea Decensi | 11 | 1966-2009 | 0.64 | 0.38 | 1.08 | Removed | --- | |
| Stomach/ Gastric | Monica Franciosi | 2 | 1966-2012 | 0.83 | 0.76 | 0.91 | Removed | --- |
| Hiroshi Noto | 3 | Until 2011 | 0.72 | 0.26 | 1.98 | Selected | High | |
| Prostate | Zhaohan Feng | 18 | These studies were done between 2011 and 2017 | 0.97 | 0.80 | 1.16 | Selected | Moderate |
| Bahareh Ghiasi | 11 | 2009-2017 | 0.89 | 0.67 | 1.17 | Removed | --- | |
| Christopher B. Chen | 26 | Inception to Aug 2015 | 1.01 | 0.86 | 1.18 | Selected | High | |
| Hiroshi Noto | 7 | Until 2011 | 0.89 | 0.66 | 1.19 | Removed | --- | |
| New meta-analysis of (Christopher B. Chen, Zhaohan Feng) | 30 | Up to 2018 | 0.94 | 0.85 | 1.04 | Selected | --- | |
| Lung | Long Yao | 13 | Until September 20, 2017 | 0.89 | 0.83 | 0.96 | Selected | Moderate |
| Shu-ping Nie | 15 | Update to Aug 2013 | 0.99 | 0.87 | 1.12 | Selected | Moderate | |
| Zhi-Jiang Zhang | 6 | 2009-2013 | 0.71 | 0.55 | 0.95 | Removed | --- | |
| Hiroshi Noto | 3 | Until 2011 | 0.67 | 0.45 | 0.99 | Removed | --- | |
| Monica Franciosi | 4 | 1966-2012 | 0.83 | 0.64 | 1.06 | Removed | --- | |
| New meta-analysis of (Long Yao, Shu-ping Nie) | 20 | Up to 2018 | 0.92 | 0.85 | 0.99 | Selected | --- | |
| Breast | Grace H. Tang | 12 | Inception to Nov 2016 | 0.93 | 0.85 | 1.03 | Selected | High |
| MohammadMoradi-Joo | 11 | Up to June 2015 | 0.63 | 0.56 | 0.70 | Removed | --- | |
| Hiroshi Noto | 7 | Until 2011 | 0.98 | 0.80 | 1.20 | Removed | --- | |
| Andrea Decensi | 11 | 1966-2009 | 0.70 | 0.28 | 1.77 | Removed | --- | |
| Nananda F Col | 7 | 1966-2009 | 0.83 | 0.71 | 0.97 | Removed | --- | |
| Monica Franciosi.ob | 9 | 1966-2012 | 0.97 | 0.88 | 1.08 | Removed | --- | |
| Esophagus | Monica Franciosi | 2 | 1966-2012 | 0.90 | 0.83 | 0.98 | Selected | Moderate |
| Bladder | Hiroshi Noto | 3 | Until 2011 | 0.94 | 0.64 | 1.38 | Selected | High |
| Cervical | Wen, Q | 2 | Last search was performed on August 15, 2018 | 0.60 | 0.43 | 0.83 | Selected | High |
| Endometrial | Wen, Q | 6 | Last search was performed on August 15, 2018 | 0.71 | 0.29 | 1.74 | Removed | --- |
| Tain, J | 6 | Through Oct 2017 | 1.29 | 1.16 | 1.44 | Removed | --- | |
| Chu, D | 7 | Between 1980 and July 2016 | 1.05 | 0.82 | 1.35 | Selected | High | |
| All Cancer | Bindiya Thakkar | RCT (2) | Until 2012 | 1.01 | 0.81 | 1.26 | Removed | --- |
| Cohort (9) | 0.7 | 0.67 | 0.73 | Removed | --- | |||
| Case-control (13) | 0.90 | 0.84 | 0.98 | Removed | --- | |||
| Lang Wu | 39 | --- | 0.86 | 0.83 | 0.9 | Removed | --- | |
| Mekuria, AN | 8 | Until Dec 2018 | 0.76 | 0.54 | 1.07 | Removed | --- | |
| Chai, S | 84 | Inception to 23 June 2017 | 0.32 | 0.07 | 1.38 | Removed | --- |
RCT=randomized control trial