Lack of an Association between Passive Smoking and Incidence of Female Breast Cancer in Non-Smokers: Evidence from 10 Prospective Cohort Studies

<div><p>Background</p><p>Several case-control studies have suggested that passive smoking may increase the incidence of female breast cancer. However, the results of cohort studies have been inconsistent in establishing an association. The present study evaluated the association between passive smoking and incidence of female breast cancer through a meta-analysis of prospective cohort studies.</p><p>Methods</p><p>Relevant articles published before August 2012 were identified by searching the electronic databases PubMed, Embase, and Web of Science. Pooled relative risks (RRs) were determined with either a fixed or random effects model and were used to assess the strength of the association. Sensitivity and subgroup analyses according to ethnicity, menopausal status, and the period and place of exposure to passive smoking were also performed.</p><p>Results</p><p>Ten prospective cohort studies involving 782 534 female non-smokers were included in the meta-analysis and 14 831 breast cancer cases were detected. Compared with the women without exposure to passive smoking, the overall combined RR of breast cancer was 1.01 (95% confidence interval: 0.96 to 1.06, P = 0.73) among women with exposure to passive smoking. Similar results were achieved through the subgroup analyses. No evidence of publication bias was observed.</p><p>Conclusion</p><p>The results suggest that passive smoking may not be associated with increased incidence of breast cancer. However, the present conclusion should be considered carefully and confirmed with further studies.</p></div

The characteristics of the included prospective cohort studies.

<p>BMI: Body mass index; CI: Confidence interval; NA: Not available; NOS: Newcastle-Ottawa-Scale; RR: Relative risk; US: United States.</p>*<p>Multi-countries contain Sweden, Denmark, Norway, the Netherlands, UK, France, Germany, Spain, Italy, and Greece.</p>#<p>Number of non-smoking women.</p

Flow chart of literatures selection.

<p>Flow chart shows literature search for prospective cohort studies of passive smoking in relation to incidence of breast cancer.</p

Subgroup analyses of meta-analysis.

<p>CI: Confidence interval; RR: Relative risk.</p

Forest plot of overall pooled RR.

<p>Forest plot shows association between passive smoking and incidence of breast cancer. CI: confidence interval; RR: relative risk.</p

Impact of <i>Schistosoma mansoni</i> on Malaria Transmission in Sub-Saharan Africa

<div><p>Background</p><p>Sub-Saharan Africa harbors the majority of the global burden of malaria and schistosomiasis infections. The co-endemicity of these two tropical diseases has prompted investigation into the mechanisms of coinfection, particularly the competing immunological responses associated with each disease. Epidemiological studies have shown that infection with <i>Schistosoma mansoni</i> is associated with a greater malaria incidence among school-age children.</p><p>Methodology</p><p>We developed a co-epidemic model of malaria and <i>S. mansoni</i> transmission dynamics which takes into account key epidemiological interaction between the two diseases in terms of elevated malaria incidence among individuals with <i>S. mansoni</i> high egg output. The model was parameterized for <i>S. mansoni</i> high-risk endemic communities, using epidemiological and clinical data of the interaction between <i>S. mansoni</i> and malaria among children in sub-Saharan Africa. We evaluated the potential impact of the <i>S. mansoni</i>–malaria interaction and mass treatment of schistosomiasis on malaria prevalence in co-endemic communities.</p><p>Principal Findings</p><p>Our results suggest that in the absence of mass drug administration of praziquantel, the interaction between <i>S. mansoni</i> and malaria may reduce the effectiveness of malaria treatment for curtailing malaria transmission, in <i>S. mansoni</i> high-risk endemic communities. However, when malaria treatment is used in combination with praziquantel, mass praziquantel administration may increase the effectiveness of malaria control intervention strategy for reducing malaria prevalence in malaria- <i>S. mansoni</i> co-endemic communities.</p><p>Conclusions/Significance</p><p>Schistosomiasis treatment and control programmes in regions where <i>S. mansoni</i> and malaria are highly prevalent may have indirect benefits on reducing malaria transmission as a result of disease interactions. In particular, mass praziquantel administration may not only have the direct benefit of reducing schistosomiasis infection, it may also reduce malaria transmission and disease burden.</p></div

The impact of the interaction between <i>S. mansoni</i> and malaria on the effectiveness of ACT for reducing malaria prevalence and symptomatic malaria episodes.

<p>We compared (A) the proportional reduction of malaria prevalence with and without interaction and (B) the increase in symptomatic episodes of malaria due to elevated susceptibility to malaria mediated by <i>S. mansoni</i> infection. <i>S. mansoni</i> high worm burden was assumed to increase the risk of malaria infection by 85% , consistent with epidemiological studies <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003234#pntd.0003234-Sokhna1" target="_blank">[6]</a>.</p

The impact of mass praziquantel administration on malaria prevalence over a six-year intervention period.

<p>The proportion of symptomatic malaria cases that received treatment was 70%. Interaction between <i>S. mansoni</i> and malaria and the effect on malaria prevalence for annual entomological inoculation rate (AEIR) equals (A) 10 infective bites per person annually and (B) 100 infective bites per person annually.</p

Lack of an Association between Angiotensin Receptor Blocker Based Therapy and Increased Risk of Cancer: Evidence from Large Observational Studies

<div><p>Background</p><p>A previous meta-analysis of randomized controlled studies that were not designed to investigate cancer as a primary outcome suggested that ARB-based therapy is associated with increased risk of cancer; however, results of recent observational studies considering the association have been contradictory. This study sought to evaluate the association between angiotensin receptor blocker (ARB)-based therapy and risk of cancer by conducting a meta-analysis of observational studies.</p><p>Methods</p><p>Relevant articles published before February 2014 were identified by searching PubMed and the Cochrane Library. Pooled relative risks (RRs) were determined using a random effects model and were used to assess the strength of association between use of ARB-based therapy and risk of cancer.</p><p>Results</p><p>Six retrospective cohort studies involving a total of 3,827,109 participants and four case-control studies involving a total of 193,029 cases were included. The present study found that ARB-based therapy was not significantly associated with an increased risk of cancer (RR = 0.87, 95%CI: [0.75, 1.01]). However, an analysis including only cohort studies suggested a significantly decreased risk of cancer among individuals with any history of ARB use as compared to those with no history of ARB use (RR = 0.80, 95%CI: [0.55, 0.95]); no significant association was found between ARB use and risk of cancer when the case-control studies were separately considered (RR = 1.03, 95%CI: [0.93, 1.13]). Subgroup analyses showed that use of ARB-based therapy was associated with decreased risk of lung cancer (RR = 0.81, 95%CI: [0.69, 0.94]); however, no significant associations were found with the other cancer sites investigated. Furthermore, no association was observed upon adjustment by type of ARB drug. No publication bias was detected.</p><p>Conclusion</p><p>Overall, ARB-based therapy was not associated with increased risk of cancer. However, its use may be related to decreased incidence of lung cancer; this finding should be considered carefully and confirmed with further studies.</p></div

Forest plot of ARB-based therapy and risk of cancer.

<p>Forest plot shows association between ARB-based therapy and risk of cancer. CI = confidence interval; ES = estimates.</p