Elsevier

Annals of Oncology

Volume 17, Issue 7, July 2006, Pages 1039-1050
Annals of Oncology

reviews
Occupational silica exposure and lung cancer risk: a review of epidemiological studies 1996–2005

https://doi.org/10.1093/annonc/mdj125Get rights and content
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Abstract

Background: In 1997, a Monograph from the International Agency for Research on Cancer (IARC) classified occupational exposure to crystalline silica as carcinogenic to humans. Large amounts of epidemiological data have been published subsequently.

Methods: We conducted a systematic review of epidemiological investigations on silica exposure and lung cancer risk published after the IARC Monograph, including 28 cohort, 15 case–control and two proportionate mortality ratio (PMR) studies. These were identified in the available literature.

Results: The pooled RR of lung cancer, calculated using random effects models, from all cohort studies considering occupational exposure to silica was 1.34. The RRs were 1.69 in cohort studies of silicotics only, 1.25 in studies where silicosis status was undefined and 1.19 among non silicotic subjects. The pooled RR was 1.41 for all case–control studies. The RRs were 3.27 in case–control studies of silicotics only, 1.41 in studies where silicosis status was undefined and 0.97 among non silicotic subjects. The RR was 1.24 for PMR studies.

Conclusions. In this re-analysis, the association with lung cancer was consistent for silicotics, but the data were limited for non silicotic subjects and not easily explained for undefined silicosis status workers. This leaves open the issue of dose–risk relation and pathogenic mechanisms and supports the conclusion that the carcinogenic role of silica per se in absence of silicosis is still unclear.

Key words

case–control studies
cohort studies
lung neoplasms
silica
silicosis
systematic review

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