Cohort studies on cancer mortality of digestive system among workers exposed to asbestos: a meta-analysis / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>To determine if there are excessive risks of malignant tumors or not among workers exposed to asbestos by applying a meta-analysis technique.</p><p><b>METHODS</b>All data meeting the criteria of cohort studies on cancer mortality of digestive system among workers exposed to asbestos would be incorporated into the meta-analysis. The pooled standardized mortality ratios (SMR) and their corresponding 95% confidence intervals (CIs) for main cancer sites of digestive system were calculated by using two approaches of un-weighted ratio and random effects model. The heterogeneity and its sources of the results were examined with a Q-statistic and Z-score test.</p><p><b>RESULTS</b>69 asbestos-exposed cohorts were summarized. The significantly elevated meta-SMR for all deaths (1.16), all cancers (1.42), cancer of digestive system (1.15) and cancer of stomach (1.20) among workers exposed to chrysotile alone or mixed asbestos were observed (P < 0.01). The stomach cancer SMR was significantly increased in the asbestos cement workers, the screening mine workers and the insulators, (1.27, 1.21 and 2.13 respectively) (P < 0.05). meta-SMR for cancers at other sites of digestive system including esophagus, colon, rectum and liver were not significant.</p><p><b>CONCLUSION</b>There are likely excessive risks of cancer of stomach among workers exposed to asbestos. However, there is likely no convincing indication of an etiological association between asbestos exposure and cancers at other sites of digestive system.</p>

A meta-analysis of cohort studies on cancer mortality among workers exposure to chrysotile fiber alone / 中华预防医学杂志

<p><b>OBJECTIVE</b>To determine there was excessive risk of malignant tumors or not among workers exposure to chrysotile fiber alone by applying a meta-analysis technique.</p><p><b>METHODS</b>All data meeting the criteria of cohort studies on cancer mortality among workers exposed only to chrysotile would incorporate into the meta-analysis. The pooled standardized mortality ratios (SMR) and their corresponding 95% confidence intervals (95% CI) for main cancer sites were calculated using two approaches of unweighted ratio and random effects model. The heterogeneity and its sources of the results were examined with a Q-statistic and Z-score test.</p><p><b>RESULTS</b>26 chrysotile-exposed alone cohorts were summarized. The significantly elevated meta-SMRs for all deaths (1.28), all cancers (1.26), cancers of respiratory organs (2.24), cancer of lung (2.29) and cancer of stomach (1.27) were observed. The significantly elevated meta-SMRs for lung cancer within occupational strata were observed among textile workers (3.64), asbestos products manufacturers (3.07), miners and millers (2.24), cement products workers (1.22), and for stomach cancer among asbestos products manufacturers (1.48). Meta-SMRs for cancers at other sites were not significant.</p><p><b>CONCLUSION</b>There were excessive risks of lung cancer and mesothelioma among workers exposure to chrysotile fiber alone, and likely no convincing indication of an etiological association between chrysotile exposure and cancers at other sites.</p>

Cohort studies on cancer mortality among workers exposed only to chrysotile asbestos: a meta-analysis / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To determine whether there was excessive risk of cancer among workers exposed to chrysotile fiber alone by applying a meta-analysis technique.</p><p><b>METHODS</b>All data meeting the criteria of cohort studies on cancer mortality among workers exposed only to chrysotile were incorporated into meta-analysis. Pooled standardized mortality ratios (SMRs) and their corresponding 95% confidence intervals (CIs) for main cancer sites were calculated using two approaches of unweighted ratio and random effect model. The heterogeneity and its sources of the results were examined with a Q-statistic and Z-score test. The dose-response effect as reflected in the percentage of all deaths due to mesothelioma served as a proxy measure of chrysotile exposure.</p><p><b>RESULTS</b>A cohort of twenty six workers exposed to chrysotile alone was summarized. The significantly elevated meta-SMRs for all deaths (1.27), all cancers (1.28), cancers of respiratory organs (2.51), cancers of lung (2.35) and cancers of stomach (1.24) were observed. The significantly elevated meta-SMRs for lung cancer within occupational strata were observed among textile workers (3.55), asbestos product manufacturers (3.30), miners and millers (2.24), cement product workers (1.22), and for stomach cancer among asbestos product manufacturers (1.49). Meta-SMRs for cancers at other sites were not significant. Meta-SMR for lung cancer showed an increasing trend with an elevated percentage of all deaths from mesothelioma, but no such trend for stomach cancer.</p><p><b>CONCLUSION</b>There are excessive risks of lung cancer and mesothelioma among workers exposed to chrysotile fiber alone, and likely no convincing indication of an etiological association between chrysotile exposure and cancers at other sites.</p>