Statins and risk of cancer: A meta-analysis of randomized, double-blind, placebo-controlled trials.

PURPOSE: Several meta-analyses of randomized controlled trials (RCTs) reported no association between the use of statins and the risk of cancer. However, they included open-label RCTs, which did not use placebo as a control group. This study aimed to evaluate the effect of statins on cancer risk using a meta-analysis of randomized, double-blind, placebo-controlled trials (RDBPCTs). METHODS: We searched PubMed, EMBASE, and the Cochrane Library in March 2016. Two individual authors reviewed and selected RDBPCTs based on selection criteria. RESULTS: Out of 676 retrieved articles, a total of 21 RDBPCTs with 65,196 participants (32,618 in the statin group and 32,578 in the placebo group) were included in the meta-analysis. Overall, we found that there was no significant association between the use of statins and the risk of cancer (relative risk 0.97, 95% confidence interval 0.92-1.02, I2 = 0.0%) in a fixed-effect meta-analysis. In addition, in the subgroup meta-analyses, no beneficial effect of statins was observed when analyzed by statin type, country, follow-up period, methodological quality, underlying diseases/population, and type of cancer. CONCLUSIONS: The current meta-analysis of RDBPCTs found that there was no association between the use of statins and the risk of cancer.

Erroneous conclusions about the association between light alcohol drinking and the risk of cancer: comments on Bagnardi et al.'s meta-analysis.

Based on the current best evidence, Bagnardi et al's conclusions that "light drinking increases the risk of cancer of oral cavity and pharynx, esophagus, and female breast." are erroneous except for female breast cancer. Further large prospective studies are necessary to confirm this association.

Prophylactic and therapeutic efficacy of pyridoxine supplements in the management of hand-foot syndrome during chemotherapy: a meta-analysis.

BACKGROUND: Hand-foot syndrome (HFS) is a common cutaneous side effect of certain systemic chemotherapeutic agents. AIM: To assess the efficacy of pyridoxine supplements in the management of HFS. METHODS: We searched PubMed, EMBASE and the Cochrane Central Register of Controlled Trials for studies reporting the efficacy of pyridoxine supplements to manage HFS. We performed a meta-analysis using HFS incidence and improvement rates to measure the preventive and treatment efficacy of pyridoxine supplementation. RESULTS: We assessed eight studies [two retrospective studies, two prospective comparative trials and four randomized controlled trials (RCTs)] for preventive efficacy and three studies (one RCT and two non-RCTs) for treatment efficacy. A random-effects meta-analysis did not find any significant association between prophylactic pyridoxine supplementation and HFS development [relative risk (RR) = 0.95; 95% CI 0.87-1.05) or any significant preventive efficacy against HFS in subgroup meta-analyses of study design, chemotherapeutic agents, pyridoxine dose, HFS severity, publication year or observation period. However, pyridoxine did show significant efficacy in treating HFS (RR = 1.75; 95% CI 1.09-2.80), but did not show efficacy in the only RCT (RR = 1.12; 95% CI 0.58-2.14). CONCLUSIONS: We found no clinical evidence to support the use of pyridoxine supplements to prevent HFS during chemotherapy.

Efficacy and safety of pharmacotherapy for smoking cessation among pregnant smokers: a meta-analysis.

BACKGROUND: The efficacy and safety of pharmacotherapy for smoking cessation among pregnant smokers has not yet been established. OBJECTIVE: To investigate the efficacy and safety of pharmacotherapy for smoking cessation among pregnant smokers. SEARCH STRATEGY: A search was made of PubMed, Embase and CENTRAL in June 2011. SELECTION CRITERIA: Randomised controlled trials (RCTs), quasi-RCTs and retrospective or prospective controlled studies were included. DATA COLLECTION AND ANALYSIS: The main analyses were designed to examine the efficacy of pharmacotherapy for smoking cessation among pregnant smokers based on the longest follow-up data available and from data obtained at the latest available time-point in pregnancy in each study. MAIN RESULTS: Of 74 articles identified from the databases, seven studies (five RCTs, one quasi-RCT and one prospective study) involving a total of 1386 pregnant smokers, 732 in the intervention groups and 654 in the control groups, were included in the final analyses. In a fixed-effects meta-analysis of all seven studies based on the longest follow-up data available, pharmacotherapy had a significant effect on smoking cessation (relative risk [RR] 1.80; 95% confidence interval [CI] 1.32-2.44). Subgroup meta-analysis by type of study design also showed similar findings for RCTs (RR 1.48; 95% CI 1.04-2.09) and other types of studies (RR 3.25; 95% CI 1.65-6.39). The abstinence rate at late pregnancy in the intervention ranged from 7 to 22.6% (mean abstinence rate 13.0%; 95% CI 10.9-15.2%). A few minor adverse effects and serious adverse effects were reported in several studies. AUTHOR'S CONCLUSIONS: This study indicates that there may be clinical evidence to support the use of pharmacotherapy for smoking cessation among pregnant smokers. Further RCTs are needed.

Vitamin or antioxidant intake (or serum level) and risk of cervical neoplasm: a meta-analysis.

BACKGROUND: Case-control studies have reported the preventive effect of vitamin or antioxidant intake on cervical neoplasms such as cervical intraepithelial neoplasia (CIN) and invasive cervical cancer. However, the findings are inconsistent. OBJECTIVE: To investigate quantitative effects of vitamin or antioxidant intake on cervical neoplasm using meta-analysis. SEARCH STRATEGY: We searched PubMed, EMBASE and the Cochrane Library in November 2008. All articles searched were independently reviewed and selected by two evaluators according to predetermined selection criteria. SELECTION CRITERIA: We included case-control studies reporting an association between vitamin or antioxidant intake (or serum level) and cervical neoplasm risk and reporting the adjusted odds ratios (OR) and 95% confidence intervals (CI), whenever possible. DATA COLLECTION AND ANALYSIS: After retrieval of data from selected articles, we performed a meta-analysis using both fixed-effects and random- effects models. MAIN RESULTS: Of 274 articles meeting our initial criteria, we included 22 case-control studies involving a total of 10,073 participants. In meta-analyses by type of vitamin or antioxidant, a significant preventive effect on cervical neoplasm was found in intakes of vitamin B12 (OR 0.35, 95% CI 0.19-0.63; n=2), vitamin C (OR 0.67, 95% CI 0.55-0.82; n=8), vitamin E (OR 0.56, 95% CI 0.35-0.88; n=10), and beta-carotene (OR 0.68, 95% CI 0.55-0.84; n=9). AUTHORS' CONCLUSIONS: The findings of this meta-analysis indicate that overall, there were preventive effects of vitamin or antioxidant intake on cervical neoplasms in case-control studies.

Aspirin use and risk for lung cancer: a meta-analysis.

BACKGROUND: Aspirin has received increasing attention owing to its potential as a chemopreventive agent against lung cancer. Previous observational studies have reported inconsistent findings on this issue. We investigated the association between aspirin use and risk for lung cancer by conducting a meta-analysis. PATIENTS AND METHODS: Relevant studies were identified by searching Medline, EMBASE, and Cochrane Library to December 2009. We also reviewed relevant bibliographies from the retrieved articles. Two authors independently extracted data and assessed study quality. Disagreements were resolved by consensus. RESULTS: Fifteen studies (six case-control studies and nine prospective cohort studies) were included in the final meta-analysis. When all studies were pooled, the odds ratio (OR) of aspirin use for lung cancer risk was 0.86 [95% confidence interval (CI) 0.76-0.98]. In subgroup meta-analyses, there was no association between aspirin use and lung cancer risk among cohort studies (relative risk, 0.97; 95% CI 0.87-1.08), while there was a significant association among case-control studies (OR, 0.74; 95% CI 0.57-0.99). In a subgroup meta-analysis by quality of study methodology, a significant protective effect of aspirin use on lung cancer was observed only among eight low-quality studies (OR, 0.82; 95% CI 0.68-0.99), but not among seven high-quality studies (OR, 0.90; 95% CI 0.76-1.07). CONCLUSIONS: Overall, the findings of this meta-analysis support that there was no association between aspirin use and lung cancer risk. Our findings should be confirmed in future prospective cohort studies or randomized, controlled trials.

Effects of antioxidant supplements on cancer prevention: meta-analysis of randomized controlled trials.

BACKGROUND: This meta-analysis aimed to investigate the effect of antioxidant supplements on the primary and secondary prevention of cancer as reported by randomized controlled trials. METHODS: We searched Medline (PubMed), Excerpta Medica database, and the Cochrane Review in October 2007. RESULTS: Among 3327 articles searched, 31 articles on 22 randomized controlled trials, which included 161 045 total subjects, 88 610 in antioxidant supplement groups and 72 435 in placebo or no-intervention groups, were included in the final analyses. In a fixed-effects meta-analysis of all 22 trials, antioxidant supplements were found to have no preventive effect on cancer [relative risk (RR) 0.99; 95% confidence interval (CI) 0.96-1.03). Similar findings were observed in 12 studies on primary prevention trials (RR 1.00; 95% CI 0.97-1.04) and in nine studies on secondary prevention trials (RR 0.97; 95% CI 0.83-1.13). Further, subgroup analyses revealed no preventive effect on cancer according to type of antioxidant, type of cancer, or the methodological quality of the studies. On the other hand, the use of antioxidant supplements significantly increased the risk of bladder cancer (RR 1.52; 95% CI 1.06-2.17) in a subgroup meta-analysis of four trials. CONCLUSIONS: The meta-analysis of randomized controlled trials indicated that there is no clinical evidence to support an overall primary and secondary preventive effect of antioxidant supplements on cancer. The effects of antioxidant supplements on human health, particularly in relation to cancer, should not be overemphasized because the use of those might be harmful for some cancer.

Soy intake and risk of endocrine-related gynaecological cancer: a meta-analysis.

BACKGROUND: Epidemiology studies have reported associations between soy intake and the risk of endocrine-related gynaecological cancers. However, to date there have been no quantitative meta-analyses reported regarding this topic. OBJECTIVES: We investigated the quantitative associations between soy food intake and the risk of endometrial cancer and ovarian cancer by a meta-analysis of case-control studies and cohort studies. SEARCH STRATEGY: We searched MEDLINE (PubMed), EMBASE and the Cochrane Library during October 2008 using common keywords related to soy intake and endometrial or ovarian cancer. Two evaluators independently reviewed and selected articles, based on predetermined selection criteria. SELECTION CRITERIA: Included studies met all of the following criteria: (1) a case-control study or cohort study (to date, no randomized controlled trials have been reported); (2) investigated the associations between 'soy or soy product intake' and 'endometrial cancer' or 'ovarian cancer'; (3) reported outcome measures with adjusted odds ratios (OR) or relative risks (RR) and 95% confidence intervals (CI). DATA COLLECTION AND ANALYSIS: We investigated the associations between the overall soy intake (highest versus lowest intake) and the risk of endocrine-related gynaecological cancers (endometrial or ovarian cancer) as the main analysis. We also performed subgroup analyses by type of cancer (endometrial or ovarian), type of study design (case-control or cohort) and type of soy intake (soy foods or soy constituents). MAIN RESULTS: Out of 477 articles that met our initial criteria, a total of seven epidemiology studies consisting of five case-control studies and two cohort studies were included in the final analyses. Compared with the lowest soy intake, the OR for the highest soy intake was 0.61 (95% CI, 0.53-0.72) of all endocrine-related cancers among seven studies; 0.70 for endometrial cancer (95% CI, 0.57-0.86) and 0.52 for ovarian cancer (95% CI, 0.42-0.66) in the fixed-effects meta-analyses. The subgroup analyses by study design showed similar findings among the case-control studies (OR, 0.62; 95% CI, 0.53-0.73) and the cohort studies (OR, 0.57; 95% CI, 0.36-0.90). AUTHOR'S CONCLUSIONS: The results of the current study showed protective effects of soy intake on the risk for endocrine-related gynaecological cancers. Additional larger prospective studies are now needed.