Parity and pancreatic cancer risk: evidence from a meta-analysis of twenty epidemiologic studies.
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ABSTRACT:
SUBMITTER: Zhu B
PROVIDER: S-EPMC4060503 | biostudies-other | 2014
REPOSITORIES: biostudies-other
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Project description:BackgroundPrevious epidemiologic studies have reported inconsistent results between parity and pancreatic cancer (PC) risk. To our knowledge, a comprehensive and quantitative assessment of this association has not been conducted.MethodsRelevant published studies of parity and PC were identified using MEDLINE (PubMed) and Web of Science databases until November 2013. Two authors (H-BG and LW) independently assessed eligibility and extracted data. Eleven prospective and 11 case-control studies reported relative risk (RR) estimates and 95% confidence intervals (CIs) of PC associated with parity. Fixed- and random-effects models were used to estimate the summary RR depending on the heterogeneity of effects.ResultsThe summary RR for PC comparing the highest versus lowest parity was 0.86 (95% CI: 0.73-1.02; Q = 50.49, P<0.001, I2 = 58.4%). Significant inverse associations were also observed in the studies that adjusted for cigarette smoking (RR = 0.81; 95% CI: 0.68-0.98), Type 2 diabetes mellitus (RR = 0.83; 95% CI: 0.75-0.93), and those that included all confounders or important risk factors (RR = 0.85; 95% CI: 0.76-0.96). Additionally, in the dose-response analysis, the summary RR for per one live birth was 0.97 (95% CI: 0.94-1.01; Q = 62.83, P<0.001, I2 = 69.8%), which also indicated a borderline statistically significant inverse effect of parity on PC risk. No evidence of publication bias and significant heterogeneity between subgroups were detected by meta-regression analyses.ConclusionIn summary, these findings suggest that higher parity is associated with a decreased risk of PC. Future large consortia or pooled studies are warranted to fully adjust for potential confounders to confirm this association.
| S-EPMC3962437 | biostudies-literature
Project description:Evidence on the association between dietary fiber intake and pancreatic cancer risk has been controversial. Therefore, we carried out this meta-analysis to summarize available evidence from epidemiologic studies on this point. Relevant studies were identified by searching PubMed, Embase and Web of Science databases as well as by reviewing the rence lists of relevant articles. Random or fixed-effects model was used to calculate the summary risk estimates and 95% confidence intervals (CIs). This meta-analysis included one cohort and thirteen case-control studies which involving a total of 3287 subjects with pancreatic cancer. After summarizing the risk estimates of these studies, we yielded a significant association between dietary fiber intake and pancreatic cancer risk among case-control studies (odds ratio = 0.54; 95%CI = 0.44-0.67; I(2) = 41.4%; P = 0.043) but a non-significant result in cohort study (hazard ratio = 1.01; 95%CI = 0.59-1.74). Additionally, significant inverse associations were observed when we carried out the stratify analyses by the study characteristics and adjustment for potential confounders among case-control studies. Given only one cohort study included in the present meta-analysis, further prospective-designed studies should validate our findings and report more detail results, including those for subtypes of fiber, the risk estimates which corrected the impact of measurement errors and fully adjust for the potential confounders.
| S-EPMC4451698 | biostudies-literature
Project description:The association between parity and endometrial cancer risk is inconsistent from observational studies. We aimed to quantitatively assess the relationship by summarizing all relevant epidemiological studies. PubMed (MEDLINE), Embase and Scopus were searched up to February 2015 for eligible case-control studies and prospective studies. Random-effects model was used to pool risk estimations. Ten prospective studies, 35 case-control studies and 1 pooled analysis of 10 cohort and 14 case-control studies including 69681 patients were identified. Pooled analysis revealed that there was a significant inverse association between parity and risk of endometrial cancer (relative risk (RR) for parous versus nulliparous: 0.69, 95% confidence interval (CI) 0.65-0.74; I(2) = 76.9%). By evaluating the number of parity, we identified that parity number of 1, 2 or 3 versus nulliparous demonstrated significant negative association (RR = 0.73, 95% CI 0.64-0.84, I(2)?= 88.3%; RR = 0.62, 95% CI 0.53-0.74, I(2)?= 92.1%; and RR = 0.68, 95% CI 0.65-0.70, I(2) = 20.0% respectively). The dose-response analysis suggested a nonlinear relationship between the number of parity and endometrial cancer risk. The RR decreased when the number of parity increased. This meta-analysis suggests that parity may be associated with a decreased risk of endometrial cancer. Further studies are warranted to replicate our findings.
| S-EPMC4642705 | biostudies-other
Project description:Although observational studies have assessed the relationship between parity and thyroid cancer risk, the findings are inconsistent. To quantitatively assess the association, we conducted a systematic review and meta-analysis. PubMed and Embase were searched up to January 2015. Prospective or case-control studies that evaluated the association between parity and thyroid cancer risk were included. We used the fixed-effects model to pool risk estimates. After literature search, 10 prospective studies, 12 case-control studies and 1 pooled analysis of 14 case-control studies including 8860 patients were identified. The studies had fair methodological quality. Pooled analysis suggested that there was a significant association between parity and risk of thyroid cancer (RR for parous versus nulliparous: 1.09, 95% CI 1.03-1.15; I2=33.4%). The positive association persisted in almost all strata of subgroup analyses based on study design, location, study quality, type of controls, and confounder adjustment, although in some strata statistical significance was not detected. By evaluating the number of parity, we identified that both parity number of 2 versus nulliparous and parity number of 3 versus nulliparous demonstrated significant positive associations (RR=1.11, 95% CI 1.01-1.22; I2=31.1% and RR=1.16, 95% CI 1.01-1.33; I2=19.6% respectively). The dose-response analysis suggested neither a non-linear nor linear relationship between the number of parity and thyroid cancer risk. In conclusion, this meta-analysis suggests a potential association between parity and risk of thyroid cancer in females. However, the lack of detection of a dose-response relationship suggests that further studies are needed to better understand the relationship.
| S-EPMC4831293 | biostudies-other
Project description: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.
| S-EPMC3787107 | biostudies-literature
Project description:A number of human and animal in vitro or in vivo studies have investigated the relationship between dietary choline and betaine and cancer risk, suggesting that choline and betaine consumption may be protective for cancer. There are also a few epidemiologic studies exploring this relationship, however, with inconsistent conclusions. The PubMed and Embase were searched, from their inception to March 2016, to identify relevant studies and we brought 11 articles into this meta-analysis eventually. The pooled relative risks (RRs) of cancer for the highest versus the lowest range were 0.82 (95% CI, 0.70 to 0.97) for choline consumption only, 0.86 (95%CI, 0.76 to 0.97) for betaine consumption only and 0.60 (95%CI, 0.40 to 0.90) for choline plus betaine consumption, respectively. Significant protective effect of dietary choline and betaine for cancer was observed when stratified by study design, location, cancer type, publication year, sex and quality score of study. An increment of 100 mg/day of choline plus betaine intake helped reduce cancer incidence by 11% (0.89, 95% CI, 0.87 to 0.92) through a dose-response analysis. To conclude, choline and betaine consumption lowers cancer incidence in this meta-analysis, but further studies are warranted to verify the results.
| S-EPMC5069558 | biostudies-literature
Project description:Although numerous in vitro studies and animal model data have suggested that flavan-3-ols, the most common subclass of flavonoids in the diet, may exert protective effects against cancer, epidemiologic studies have reported inconclusive results for the association between flavan-3-ols intake and cancer risk. Therefore, we conducted this meta-analysis of epidemiologic studies to investigate the preventive effects of flavan-3-ols on various types of cancers. A total of 43 epidemiologic studies, consisting of 25 case-control and 18 prospective cohort studies, were included. A significant inverse association was shown between flavan-3-ols intake and the risk of overall cancer (relative risk (RR) 0.935, 95%CI: 0.891-0.981). When cancer types were separately analyzed, a statistically significant protective effect of flavan-3-ols consumption was observed in rectal cancer (RR 0.838, 95%CI: 0.733-0.958), oropharyngeal and laryngeal cancer (RR 0.759, 95%CI: 0.581-0.993), breast (RR 0.885, 95%CI: 0.790-0.991) in case-control studies and stomach cancer in women (RR 0.633, 95%CI: 0.468-0.858). Our analysis indicates the potential benefits of flavan-3-ols in cancer prevention.
| S-EPMC5342000 | biostudies-literature
Project description:Analgesics are the most commonly used over-the-counter drugs worldwide with certain analgesics having cancer prevention effect. The evidence for an increased risk of developing kidney cancer with analgesic use is mixed. Using a meta-analysis design of available observational epidemiologic studies, we investigated the association between analgesic use and kidney cancer risk. We searched the MEDLINE and EMBASE databases to identify eligible case-control or cohort studies published in English until June 2012 for three categories of analgesics: acetaminophen, aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs). Study-specific effect estimates were pooled to compute an overall relative risk (RR) and its 95% confidence interval (CI) using a random-effects model for each category of the analgesics. We identified 20 studies (14 with acetaminophen, 13 with aspirin and five with other NSAIDs) that were performed in six countries, including 8,420 cases of kidney cancer. Use of acetaminophen and non-aspirin NSAIDs were associated with an increased risk of kidney cancer (pooled RR: 1.28; 95% CI: 1.15-1.44 and 1.25; 95% CI: 1.06-1.46, respectively). For aspirin use, we found no overall increased risk (pooled RR: 1.10; 95% CI: 0.95-1.28), except for non-US studies (five studies, pooled RR: 1.17; 95% CI: 1.04-1.33). Similar increases in risks were seen with higher analgesic intake. In this largest meta-analysis to date, we found that acetaminophen and non-aspirin NSAIDs are associated with a significant risk of developing kidney cancer. Further work is needed to elucidate biologic mechanisms behind these findings.
| S-EPMC3815746 | biostudies-literature
Project description:Background: One of the most frequently used medications for treating gastrointestinal disorders is proton pump inhibitor (PPI), which reportedly has potential adverse effects. Although the relationship between the use of PPIs and the risk of pancreatic cancer has been extensively investigated, the results remain inconsistent. Hence, this meta-analysis aimed to evaluate such relationship. Methods: We searched for literature and subsequently included 10 studies (seven case-control and three cohort studies; 948,782 individuals). The pooled odds ratio (OR) and 95% confidence intervals (CI) for pancreatic cancer were estimated using a random-effects model. We also conducted sensitivity analysis and subgroup analysis. Results: The pooled OR of the meta-analysis was 1.698 (95% CI: 1.200-2.402, p = 0.003), with a substantial heterogeneity (I2 = 98.75%, p < 0.001). Even when studies were excluded one by one, the pooled OR remained statistically significant. According to the stratified subgroup analyses, PPI use, and pancreatic cancer incidence were positively associated, regardless of the study design, quality of study, country, and PPI type. Conclusion: PPI use may be associated with the increased risk of pancreatic cancer. Hence, caution is needed when using PPIs among patients with a high risk of pancreatic cancer.
| S-EPMC7463819 | biostudies-literature
Project description:Multiple studies have assessed parity as a risk factor for lung cancer but results have been inconclusive. We searched MEDLINE (through August 2010) and the Institute of Scientific Information Web of Knowledge database (through April 2011) to identify studies investigating the association of parity with lung cancer and allowing the calculation of dose-response trends using a linear model. Between-study heterogeneity was assessed using Cochran's Q statistic and the I(2) index. Summary per-child relative risks (RRs) with their 95% confidence interval (CI) were estimated using random effects meta-analysis. Sixteen eligible studies (8077 lung cancer patients; 350,295 unaffected individuals) provided data for meta-analysis. There was significant between-study heterogeneity (p<0.001; I(2)=73%). The summary per livebirth RR was 0.98 (95% CI, 0.95-1.02), indicating no effect of parity on lung cancer risk. Results were consistent in case-control (n=11), RR=0.99 (95% CI, 0.94-1.04), and cohort studies (n=5), RR=0.97 (95% CI, 0.92-1.03). Studies not including small-cell lung cancer patients found a borderline protective effect of parity, RR=0.94 (95% CI, 0.88-1.00). In contrast, no effect was observed in studies including small-cell lung cancer patients, RR=1.00 (95% CI, 0.98-1.03); p for difference=0.05. Overall, there was little evidence of a dose-response relationship between increasing number of livebirths and lung cancer; however, studies have produced heterogeneous results. Future studies should include analyses in well-defined histological disease subgroups.
| S-EPMC5558442 | biostudies-literature