Relationship between exposure to ionizing radiation and mesothelioma risk: A systematic review of the scientific literature and meta-analysis.

BACKGROUND: Ionizing radiation and mesothelioma have been examined among personnel employed in nuclear power plant and patients treated by external beam radiation therapy (EBRT). The association is still controversial; the purpose of this review is to summarize the scientific evidence published in the literature regarding the relationship between ionizing radiation and incidence of mesothelioma and, if possible, estimating strongness of the association by meta-analysis of extracted data. METHODS: Articles included in the systematic review were retrieved by searching among the three main scientific databases: PubMed, Scopus, and Embase. The literature search was conducted in June 2021. A meta-analysis of random effects was conducted, stratified by exposure (EBRT, occupational exposure). The heterogeneity of the summary relative risks (RRs) was assessed using I2  statistics. Publication bias was evaluated graphically through the funnel plot. FINDINGS: The exposure to ionizing radiation could be a risk factor for mesothelioma: both for exposure to high doses for short periods (EBRT) (RR of 3.34 [95% confidence interval, CI 1.24-8.99]) and for exposure to low doses for a prolonged duration (exposure working) (RR of 3.57 [95% CI 2.16-5.89]). CONCLUSIONS: Despite the low number of mesotheliomas in the general population, the steadily increased risk among individuals exposed to radiation is still worth considering.

Interaction between occupational exposure to diesel exhaust and tobacco smoking in determining lung cancer risk: a meta-analysis.

BACKGROUND: While an association between exposure to diesel exhaust (DE) and risk of lung cancer has been reported in several studies, its interaction with tobacco smoking in determining lung cancer risk is not well characterized. This study aims at performing a systematic review and meta-analysis of results of epidemiology studies on this. METHODS: Studies included in the systematic review were identified from PubMed, Scopus, and Embase, without limitation of year of publication or language. Two reviewers independently reviewed the studies and abstracted relevant data from selected studies, applied a customized quality assessment tool and calculated the relative risks (RRs) and 95% confidence intervals (CIs) for the interaction between DE exposure and tobacco smoking on a multiplicative scale. Next, a random-effects meta-analysis of the interaction RR was conducted. RESULTS: Seven studies were included in the meta-analysis, of which two were cohort and five case-control studies. Results on the interaction were heterogeneous (I2 = 45.6%). The summary RR for interaction was 0.79 (95% CI, 0.42-1.46). There was no indication of publication bias. There was no increased risk of lung cancer among non-smoking workers exposed to DE. CONCLUSIONS: This meta-analysis suggested a less-than-multiplicative effect between DE exposure and tobacco smoking in determining lung cancer risk, but the hypothesis of multiplicative interaction cannot be rejected. The small number of relevant studies and the high heterogeneity among them prevent from definite conclusions.

Systematic review and meta-analysis of recent high-quality studies on exposure to particulate matter and risk of lung cancer.

BACKGROUND: Several aspects of the association between exposure to air pollution and risk of lung cancer remain unclear. OBJECTIVE: We aimed at performing a meta-analysis of high-quality cohort studies on exposure to particulate matter (PM) 10 and PM2.5 and risk of lung cancer. METHODS: We identified cohort studies published since 2004, that reported risk estimates of lung cancer for exposure to PM2.5 and PM10 adjusted for tobacco smoking and socioeconomic status, and conducted a meta-analysis based on random-effects models, including stratification by outcome, sex, country, tobacco smoking, and age. RESULTS: Results on PM2.5 exposure were available from 15 studies; the summary relative risk (RR) for an increase of 10 µg/m3 was 1.16 (95% confidence interval [CI] 1.09, 1.23). The corresponding RR for PM10 exposure was 1.23 (95 CI 1.05, 1.40; seven studies). A higher risk was suggested in studies based on lung cancer mortality and in studies conducted in East Asia, while no difference was shown according to sex, smoking status or age. There was no suggestion of publication bias. CONCLUSIONS: Our meta-analysis supported the hypothesis of an association between exposure to PM2.5 or PM10 and risk of lung cancer, and provided evidence that the magnitude of the risk might be higher than previously estimated, and might be modified by outcome and geographic region.

Application of epidemiological findings to individuals.

Three types of issues need to be considered in the application of epidemiology results to individuals. First, epidemiology results are subject to random error, and can be applied only to an ideal subject with average values of all variables under study, including potential confounders included in the regression models. Second, the observational nature of epidemiology makes it susceptible to systematic error, and any extrapolation to individuals would mirror the validity of the original results. Quantitative bias analysis has been proposed to assess the likelihood, direction and magnitude of bias, but this has not yet become part of the normal practice of epidemiology. Finally, external validity of the results (i.e., their application to individuals and populations other than those included in the underlying studies) needs to be addressed, including population-based factors, such as heterogeneity in exposure or disease circumstances, and individual-based factors, such as interaction of the risk factors of interest with other determinants of the disease. Similar considerations apply to the application of results of clinical trials to individual patients, although in these studies sources of systematic error are better controlled.

Correlations between pain in the back and neck/upper limb in the European Working Conditions Survey.

BACKGROUND: Recent research has suggested that wide international variation in the prevalence of disabling regional pain among working populations is driven largely by factors predisposing to musculoskeletal pain in general and not specific to individual anatomical sites. We sought to confirm this finding, using data from an independent source. METHODS: Using data from the fifth (2010) and sixth (2015) European Working Conditions Surveys, we explored correlations between the one-year prevalence of pain in the back and neck/upper limb among people of working age across 33 European countries, and between changes in pain prevalence at the two anatomical sites from 2010 to 2015. RESULTS: Each survey recruited ≥1000 participants per country, response rates ranging from 11 to 78%. In 2010, the estimated one-year population prevalence of back pain ranged from 23% in Ireland to 66% in Portugal, and that of pain in the neck/upper limb from 25% in Ireland to 69% in Finland, the prevalence of pain at the two anatomical sites being correlated across the 33 countries (r = 0.42). A similar pattern was apparent in 2015. For back pain, the percentage change in prevalence from 2010 to 2015 varied from - 41.4% (Hungary) to + 29.6% (Ireland), with a mean across countries of - 3.0%. For neck/upper limb pain, the variation was from - 41.0% (Hungary) to + 44.1% (Romania), with an average of - 0.1%. There was a strong correlation across countries in the change in pain prevalence at the two anatomical sites (r = 0.85). CONCLUSIONS: Our findings accord with the hypothesis that international variation in common pain complaints is importantly driven by factors that predispose to musculoskeletal pain in general.