Asbestos exposure and small cell lung cancer: Systematic review and meta-analysis

Asbestos is a mineral that is carcinogenic to humans. Its use has been banned in many occidental countries yet it is still produced in the United States, and materials that contain asbestos remain in many occupational settings and indoor environments. Even though asbestos carcinogenicity is well known, there is scant literature on its specific effects regarding small cell lung cancer (SCLC). We therefore conducted a systematic review and meta-analysis to determine SCLC risk among workers exposed to asbestos. A systematic search of the literature was conducted to identify studies which reported occupational exposure to asbestos and SCLC-related deaths and/or incidence. We identified seven case-control studies that included 3,231 SCLC cases; four studies reported smoking-adjusted risks. A significantly increased risk of SCLC (pooled OR 1.89; 95% CI, 1.25-2.86) was observed on pooling studies on men (six studies) that displayed moderate heterogeneity (I2 = 46.0%). Overall, our synthesis suggests that occupational exposure to asbestos significantly increases the risk of SCLC on men.