Circulating adiponectin, leptin and adiponectin-leptin ratio and endometrial cancer risk: Evidence from a meta-analysis of epidemiologic studies.

We performed this meta-analysis of epidemiologic studies to investigate the associations between circulating adiponectin, leptin and adiponectin-leptin (A/L) ratio and endometrial cancer risk. Relevant manuscripts were identified by searching PubMed and ISI Web of Science databases as well as by manual searching the references cited in retrieved manuscripts. Random-effects models were used to estimate summary odds ratio (SOR) and 95% confidence intervals (CIs) for aforementioned associations. Fourteen manuscripts with 13 studies (five nested case-control and eight case-control studies) cumulatively involving a total of 1,963 endometrial cancer cases and 3,503 noncases were included in the analyses. Overall, comparing persons with circulating concentrations of adiponectin, leptin and A/L ratio in the top tertile with persons with concentrations of these biomarkers in the bottom tertile yielded SORs of 0.47 (95% CI: 0.34-0.65; I(2) = 63.7%; n = 13), 2.19 (95% CI: 1.44-3.31; I(2) = 64.2%; n = 7),and 0.45 (95% CI: 0.24-0.86; I(2) = 90.1%; n = 5), respectively. Notably, there was an 18% reduction in risk for per each 5 µg/mL increment in circulating adiponectin concentrations (SOR = 0.82; 95% CI: 0.74-0.90; I(2) = 49%; n = 8). Stratifying by study characteristics and whether these studies considered or adjusted for potential confounders, the findings were robust in the analyses of circulating adiponectin and leptin. No evidence of publication bias was detected. In conclusion, the findings from this meta-analysis suggest that increased circulating adiponectin and A/L ratio or decreased leptin concentrations were associated with reduced risk of endometrial cancer. Further prospective designed studies are warranted to confirm our findings.

Nonlinear reduction in risk for colorectal cancer by oral contraceptive use: a meta-analysis of epidemiological studies.

PURPOSE: Although the relationship between oral contraceptive (OC) use and colorectal cancer (CRC) risk has been studied extensively, the results of epidemiological studies are controversial. Therefore, we carried out a meta-analysis of epidemiological studies to summarize the available evidence and to quantify the potential dose-response relation. METHODS: We searched PubMed database for studies of OC use and CRC risk that were published until the end of March 2014. Random- and fixed-effects models were applied to estimate summary relative risks (RRs) and 95 % confidence intervals (CIs). RESULTS: Twelve cohorts and seventeen case-control studies with a total of 15,790 CRC cases were included in the final analysis. The summary RR for the ever versus never category of OC use was 0.82 (95 % CI 0.76-0.88). Similar result was observed when we compared the longest duration of OC use with the shortest duration (RR = 0.86, 95 % CI 0.76-0.96). Furthermore, the results of stratified analysis were comparable to those of overall meta-analysis. In dose-response analysis, significant inverse associations emerged in nonlinear models for the duration of OC use and CRC (P nonlinearity = 0.001). The greatest risk reduction was observed when the duration of OC use was approximately 42 months. There was moderate heterogeneity in the analysis, and no evidence of small-study bias was observed. CONCLUSIONS: Based on the findings of this meta-analysis, ever use of OC is associated with lower risk of CRC. Additionally, there is a statistically significant nonlinear inverse association between the duration of OC use and CRC risk.

Age at menarche and risk of ovarian cancer: a meta-analysis of epidemiological studies.

Epidemiological studies have reported inconsistent associations between menarcheal age and ovarian cancer risk. To our knowledge, a meta-analysis for the association between menarcheal age and ovarian cancer has not been reported. Relevant published studies of menarcheal age and ovarian cancer were identified using MEDLINE, EMBASE and Web of Science through the end of April 2012. Two authors (T-T.G. and Q-J.W.) independently assessed eligibility and extracted data. We pooled the relative risks (RRs) from individual studies using a random-effects model and performed heterogeneity and publication bias analyses. A total of 27 observational studies consisting of 22 case-control and five cohort studies were included in our analysis. In a pooled analysis of all studies, a statistically significant inverse association was observed between menarcheal age (for the oldest compared to the youngest category) and ovarian cancer risk (RR = 0.85; 95% confidence interval [CI] = 0.75-0.97). The pooled RRs of ovarian cancer for the oldest versus the youngest categories of menarcheal age in prospective and case-control studies were 0.89 (95% CI = 0.76-1.03) and 0.84 (95% CI = 0.70-0.99), respectively. Inverse associations between menarcheal age and ovarian cancer risk were observed in most subgroups; however, the significant association was restricted to invasive and borderline serous ovarian cancer. In conclusion, findings from this meta-analysis support that menarcheal age was inversely associated with the risk of ovarian cancer. More large studies are warranted to stratify these results by different cancer grading and histotype of ovarian cancer.

Age at menarche and endometrial cancer risk: a dose-response meta-analysis of prospective studies.

Evidence between age at menarche and endometrial cancer risk have been controversial. Therefore, we conducted a meta-analysis of prospective studies to analyze the aforementioned association. Relevant studies were identified by searching PubMed and EMBASE databases until the end of June 2015. A random-effects model was used to estimate summary relative risks (RRs) and 95% confidence intervals (CIs) for associations between menarcheal age and endometrial cancer risk. Our meta-analysis included eight prospective studies involving 4553 subjects with endometrial cancer. The summarized RRs of endometrial cancer for menarcheal age were 0.68 (95%CI = 0.58-0.81, I(2) = 41.9%, P = 0.099, n = 8) when comparing women with oldest category of menarcheal age with women with youngest category of menarcheal age. Notably, there was an 4% reduction in risk for per 2 years delay in menarcheal age (summarized RR = 0.96; 95%CI = 0.94-0.98, I(2) = 45.7%, P = 0.101, n = 6). Additionally, significant inverse associations were consistent within all stratified analyses. There was no evidence of publication bias or significant heterogeneity between subgroups detected by meta-regression analyses. Our findings support the hypothesis that late menarcheal age is inversely associated with endometrial cancer risk. Further larger prospective or pooled studies are warranted to fully adjust for potential confounders and distinguish whether the associations differ by histological subtypes of endometrial cancer.

Comorbidity and survival among women with ovarian cancer: evidence from prospective studies.

The relationship between comorbidity and ovarian cancer survival has been controversial so far. Therefore, we conducted a meta-analysis to summarize the existing evidence from prospective studies on this issue. Relevant studies were identified by searching the PubMed, EMBASE, and ISI Web of Science databases through the end of January 2015. Two authors independently performed the eligibility evaluation and data abstraction. Random-effects models were used to estimate summary hazard ratios (HRs) and 95% confidence intervals (CIs) for overall survival. Eight prospective studies involving 12,681 ovarian cancer cases were included in the present study. The summarized HR for presence versus absence of comorbidity was 1.20 (95% CI = 1.11-1.30, n = 8), with moderate heterogeneity (I(2) = 31.2%, P = 0.179). In addition, the summarized HR for the highest compared with the lowest category of the Charlson's comorbidity index was 1.68 (95% CI = 1.50-1.87, n = 2), without heterogeneity (I(2) = 0%, P = 0.476). Notably, a significant negative impact of comorbidity on ovarian cancer survival was observed in most subgroup analyses stratified by the study characteristics and whether there was adjustment for potential confounders. In conclusion, the findings of this meta-analysis suggest that underlying comorbidity is consistently associated with decreased survival in patients with ovarian cancer. Comorbidity should be taken into account when managing these patients.

Breastfeeding and ovarian cancer risk: a meta-analysis of epidemiologic studies.

BACKGROUND: Epidemiologic studies have yielded inconsistent findings between breastfeeding and epithelial ovarian cancer (EOC) risk. OBJECTIVE: We performed a meta-analysis to summarize available evidence of the association between breastfeeding and breastfeeding duration and EOC risk from published cohort and case-control studies. DESIGN: Relevant published studies were identified by a search of MEDLINE through December 2012. Two authors (T-TG and Q-JW) independently performed the eligibility evaluation and data abstraction. Study-specific RRs from individual studies were pooled by using a random-effects model, and heterogeneity and publication-bias analyses were conducted. RESULTS: Five prospective and 30 case-control studies were included in this analysis. The pooled RR for ever compared with never breastfeeding was 0.76 (95% CI: 0.69, 0.83), with moderate heterogeneity (Q = 69.4, P < 0.001, I(2) = 55.3%). Risk of EOC decreased by 8% for every 5-mo increase in the duration of breastfeeding (RR: 0.92; 95% CI: 0.90, 0.95). The risk reduction was similar for borderline and invasive EOC and was consistent within case-control and cohort studies. CONCLUSIONS: Results of this meta-analysis support the hypothesis that ever breastfeeding and a longer duration of breastfeeding are associated with lower risks of EOC. Additional research is warranted to focus on the association with cancer grade and histologic subtypes of EOC.

Parity and risk of colorectal cancer: a dose-response meta-analysis of prospective studies.

BACKGROUND: Association between parity and colorectal cancer (CRC) risk has been investigated by several epidemiological studies but results are controversial, yet a comprehensive and quantitative assessment of this association has not been reported so far. METHODS: Relevant published studies of parity and CRC were identified using MEDLINE, EMBASE and Web of Science databases through end of April 2013. Two authors independently assessed eligibility and extracted data. Eleven prospective studies reported relative risk (RR) estimates and 95% confidence intervals (CIs) of CRC risk associated with parity. We pooled the RR from individual studies using fixed- or random-effects models and carried out heterogeneity and publication bias analyses. RESULTS: The summary RR for the ever parity vs. nulliparous was 0.95 (95% CI: 0.88-1.02), with no heterogeneity (Q = 9.04, P = 0.443, I (2) = 0.5%). Likewise, no significant association was yielded for the highest vs. lowest parity number (RR = 1.02, 95% CI: 0.89-1.17), with moderate heterogeneity (Q = 17.48, P = 0.094, I (2) = 37.1%). Dose-response analysis still indicated no effect of parity on CRC risk and the summary RR of per one livebirth was 0.99 (95% CI: 0.96-1.02), with moderate of heterogeneity (Q = 16.50, P<0.021, I (2) = 57.6%). Similar results were observed among all the subgroup analyses. No evidence of publication bias and significant heterogeneity between subgroups were detected by meta-regression analyses. CONCLUSION: Results of this dose-response meta-analysis of prospective studies found that there was little evidence of an association between parity and CRC risk.