Anti-diabetic medications and the risk of hepatocellular cancer: a systematic review and meta-analysis.

Several preclinical and observational studies have shown that anti-diabetic medications (ADMs) can modify the risk of hepatocellular cancer (HCC) in patients with diabetes mellitus (DM). We performed a systematic review and meta-analyses of studies evaluating the effect of metformin, thiazolidinediones (TZDs), sulfonylureas, and/or insulin on the risk of HCC. We conducted a systematic search of Medline, EMBASE, and Web of Science up to August 2012. Studies were included if they (1) evaluated and clearly defined exposure to metformin, TZDs, sulfonylureas, and/or insulin, (2) reported HCC outcomes in patients with DM, and (3) reported relative risks or odds ratio (OR) or provided data for their estimation. Summary OR estimates with 95% confidence intervals (CIs) were estimated using the random-effects model. Ten studies reporting 22,650 cases of HCC in 334,307 patients with type 2 DM were included in the analysis. Meta-analysis of observational studies showed a 50% reduction in HCC incidence with metformin use (n=8 studies; OR 0.50, 95% CI 0.34-0.73), 62% and 161% increase in HCC incidence with sulfonylurea (n=8 studies; OR 1.62, 95% CI 1.16-2.24) or insulin use (n=7; OR 2.61, 95% CI 1.46-4.65), respectively. TZDs did not modify the risk of HCC (n=4; OR 0.54, 95% CI 0.28-1.02). There was considerable heterogeneity across studies, which was partly explained by study setting, location, and whether the studies adjusted for the concomitant use of other ADMs. Post-hoc analysis of randomized controlled trials did not reveal any significant association between ADM use and risk of HCC. ADMs may modify the risk of HCC in patients with DM, especially in the Western population. However, the effect of each individual agent should be interpreted with caution owing to inherent cancer-modifying effect of the comparator group.

Anti-diabetic medications and risk of pancreatic cancer in patients with diabetes mellitus: a systematic review and meta-analysis.

OBJECTIVES: Several preclinical and observational studies have shown that anti-diabetic medications (ADMs) may modify the risk of pancreatic cancer (PaC). We performed a systematic review and meta-analysis evaluating the effect of metformin, sulfonylureas (SUs), thiazolidinediones (TZDs), and insulin on the risk of PaC in patients with diabetes mellitus (DM). METHODS: We conducted a systematic search of Medline, EMBASE, and Web of Science, up to June 2012, and published abstracts from major gastroenterology and oncology meetings from 2003 to 2012. Studies were included if they (1) evaluated and clearly defined exposure to metformin, SU, TZDs, and/or insulin, (2) reported PaC outcomes in patients with DM and (3) reported relative risks or odds ratio (OR) or provided data for their estimation. Summary OR estimates with 95% confidence intervals (CIs) were estimated using the random-effects model. RESULTS: Eleven studies (6 cohort, 3 case-control, and 2 randomized controlled trials (RCTs)) reported 1770 cases of PaC in 730,664 patients with DM. Meta-analysis of observational studies showed no significant association between metformin (n=9 studies; adjusted OR 0.76, 95% CI 0.57-1.03, P=0.073), insulin (n=7 studies; adjusted OR 1.59, 95% CI 0.85-2.96, P=0.144), or TZD (n=4 studies; adjusted OR 1.02, 95% CI 0.81-1.30, P=0.844) use and risk of developing PaC. Use of SU was associated with a 70% increase in the odds of PaC (n=8 studies; adjusted OR 1.70, 95% CI 1.27-2.28, P<0.001). There was considerable inherent heterogeneity between studies not explained by study design, setting, or comparator drug and is likely related to confounding by indication and reverse causality. The pooled analyses of the two RCTs were underpowered and provided non-significant results with wide, non-informative 95% CIs. CONCLUSIONS: Although SU seems to be associated with increased risk of PaC, meta-analysis of existing studies does not support a protective or harmful association between ADM use and risk of PaC in patients with DM. There was considerable heterogeneity across studies, and future, well-designed, prospective studies would be required to understand this association better.

Statins are associated with reduced risk of esophageal cancer, particularly in patients with Barrett's esophagus: a systematic review and meta-analysis.

BACKGROUND & AIMS: The incidence of esophageal cancer is increasing in the United States, especially among patients with Barrett's esophagus (BE). Statins might prevent this cancer. We performed a systematic review with a meta-analysis of studies that evaluated the effect of statins on the risk of esophageal cancer. METHODS: We conducted a systematic search of Medline, Embase, and Web of Science through August 2012. Studies were included if they evaluated exposure to statins, reported the development of esophageal cancer, and reported relative risks or odds ratios (OR), or provided data for their estimation. Summary OR estimates with 95% confidence intervals (CI) were calculated using the random-effects model. The analysis included 13 studies (including a post hoc analysis of 22 randomized controlled trials) reporting 9285 cases of esophageal cancer among 1,132,969 patients. RESULTS: A meta-analysis of the studies showed a significant (28%) reduction in the risk of esophageal cancer among patients who took statins (adjusted OR, 0.72; 95% CI, 0.60-0.86), although there was considerable heterogeneity among studies. In analyzing a subset of patients known to have BE (5 studies, 312 esophageal adenocarcinomas [EAC] developed in 2125 patients), statins were associated with a significant (41%) decrease in the risk of EAC, after adjusting for potential confounders (adjusted OR, 0.59; 95% CI, 0.45-0.78) with consistent results among all studies. The number needed to treat with statins to prevent 1 case of EAC in patients with BE was 389. CONCLUSIONS: Based on meta-analysis of observational studies, statin use may be associated with lower risk of esophageal cancer, particularly risk of EAC in patients with BE.

Statins are associated with a reduced risk of hepatocellular cancer: a systematic review and meta-analysis.

BACKGROUND & AIMS: Hepatocellular carcinoma (HCC) is a leading cause of cancer-related mortality worldwide. Several studies have shown that statins could have chemopreventive effects on HCC. We performed a systematic review and meta-analysis of studies that evaluated the effects of statins on the risk of HCC. METHODS: We conducted a systematic search of MEDLINE, Embase, and Web of Science through May 2012 and manually reviewed the literature. Studies were included if they evaluated and clearly defined exposure to statins, reported the incidence of HCC, and reported relative risks or odds ratios (ORs) or provided data for their estimation. Ten studies reporting 4298 cases of HCC in 1,459,417 patients were analyzed. Summary OR estimates with 95% confidence intervals (CIs) were calculated using the random effects model. Statistical heterogeneity was assessed with the Cochran's Q statistic and I(2) statistic. RESULTS: Statin users were less likely to develop HCC than statin nonusers (adjusted OR, 0.63; 95% CI, 0.52-0.76), although the results were heterogeneous (P = .01, I(2) = 59%). This heterogeneity could be accounted for by study location (Asian population [n = 4]: adjusted OR, 0.52; 95% CI, 0.42-0.64; Western population [n = 6]: adjusted OR, 0.67; 95% CI, 0.53-0.85) and design (observational studies [n = 7]: adjusted OR, 0.60; 95% CI, 0.49-0.73; clinical trials [n = 3]: adjusted OR, 0.95; 95% CI, 0.62-1.45). CONCLUSIONS: Based on meta-analysis, statin use is associated with a reduced risk of HCC, most strongly in Asian but also in Western populations. Randomized clinical trials in populations at high risk for HCC (especially in Asian populations with hepatitis B) are warranted.

Bisphosphonates are associated with reduced risk of colorectal cancer: a systematic review and meta-analysis.

BACKGROUND & AIMS: Colorectal cancer (CRC) is the third most common cancer worldwide. Several preclinical and observational studies have shown that bisphosphonates may have chemopreventive effects against CRC. We performed a systematic review and meta-analysis of all studies evaluating the effect of bisphosphonates on the risk of CRC. METHODS: We conducted a systematic search of Medline, Embase, and Web of Science through August 2012 and manually reviewed the literature. Studies were included if they met the following criteria: (1) evaluated and clearly defined exposure to bisphosphonates, (2) reported CRC outcomes, and (3) reported relative risks or odds ratio (OR) or provided sufficient data for their estimation. Summary OR estimates with 95% confidence intervals (CIs) were estimated using the random-effects model. Statistical heterogeneity was assessed with the Cochran's Q and I(2) statistic. RESULTS: We analyzed data from 6 population-based observational studies reporting 20,001 cases of CRC in 392,106 patients. A meta-analysis of these studies showed a statistically significant 17% reduction in CRC incidence with bisphosphonate use (unadjusted OR, 0.83; 95% CI, 0.76-0.90), with borderline heterogeneity across studies (Cochran's Q, P = .16; I(2) = 37%). This effect persisted after correcting for multiple covariates in individual studies (adjusted OR, 0.85; 95% CI, 0.74-0.98). When the analysis was restricted to women only, use of bisphosphonates was associated with a 16% reduction in CRC incidence, which bordered on statistical significance (n = 5 studies; adjusted OR, 0.84; 95% CI, 0.70-1.01). This chemopreventive effect of bisphosphonates was observed for proximal and distal colon cancers, as well as rectal cancer, independently. CONCLUSIONS: Based on meta-analysis, bisphosphonate use is associated with a modest, but statistically significant, reduction in CRC risk.