Does exposure to asbestos cause ovarian cancer? A systematic literature review and meta-analysis.

INTRODUCTION: The asbestos and ovarian cancer relationship is not well understood because of small numbers of women exposed to asbestos, small numbers of cases, and misclassification of peritoneal mesothelioma as ovarian cancer on death certificates. The aim of this study was to conduct a meta-analysis to quantify the evidence that exposure to asbestos causes ovarian cancer.

METHODS: Fourteen cohort and two case-control studies were identified in Medline searches from 1950 to 2008.

RESULTS: Statistically significant excess mortality was reported in four of the cohort studies, all of which determined their outcomes from the death certificate. Peritoneal mesotheliomas were reported in these studies, two of which reexamined pathology specimens and reported disease misclassification. Exposure-response relationships were inconsistent. When all studies were included in a meta-analysis, the effect size was 1.75 (95% CI, 1.45-2.10) attenuating to 1.29 (95% CI, 0.97-1.73) in studies with confirmed ovarian cancers.

CONCLUSION: Taken without further analysis, women thought to have ovarian cancer had an increased rate in the meta-analysis if reporting having been exposed to asbestos, compared with reference populations. This result may have occurred because of disease misclassification.