Abstract 831: Occupational-related exposure to benzene and risk of breast cancer: Systematic review and meta-analysis

Abstract

Abstract Purpose: Benzene is a recognized carcinogen as evidenced by its association with leukemia; however, its association with breast cancer is not well established. Hence, a meta-analysis of cohort and case-control studies was performed to determine the association between benzene exposure and the risk of breast cancer. Methods: A systematic literature review was conducted and 7221 publications were identified, from which 21 cohort and case-control studies were retained, and evaluated using meta-analyses (fixed effects model). PECOS criteria and STROBE guidelines were followed, and the study protocol was registered in the PROSPERO database (Registration No. 379720). Study quality was assessed using a modified Newcastle-Ottawa scale (NOS). Results: The summary relative risk (RR) for ever-benzene exposure was 1.08 (95% CI=1.02-1.14, I2=43.6%, n=21); corresponding RR for cancer incidence and mortality were 1.08 (95% CI=1.02-1.14, I2=58.6%, n=15) and 1.09 (95% CI=0.87-1.38, I2<0.001%, n=9), respectively. These main results were confirmed in sub-analyses by geographical region, industry type, publication year, and levels of exposure. No heterogeneity was detected amongst geographical regions (p-het=0.19), industry of employment (p-het=0.05) or and duration of the dose (low, high; p-het=0.64). Studies published before 2003 reported a summary RR of 1.24 (95% CI=1.13-1.37), compared to a summary RR of 1.02 (95% CI=0.95-1.08) for studies published later (p-het=0.001). Heterogeneity was observed when evaluating studies at and above, or below the NOS mean (p-het=0.00), with a summary RR of 1.25 (95% CI=1.13-1.28, I2<0.001%, n=9) for studies below the median NOS score. Sub-group analysis of study design demonstrated heterogeneous results (p-het=0.001) with a summary RR of 1.19 (95% CI=1.10-1.29, I2<0.001%, n=16) for cohort studies while compared to the findings of case-control studies. Publication bias was detected (p=0.04). Conclusions: Our meta-analysis identified an association between occupational benzene exposure and risk of breast cancer. The association was restricted to studies published before 2003, below the median NOS score, and cohort studies. Residual confounding variables cannot be excluded, which, together with potential bias, prevents conclusions of causality. Citation Format: Vincent DeStefano, Darshi Shah, Veer Shah, Monireh Sadat Seyyedsalehi, Mattia Bonetti, Paolo Boffetta. Occupational-related exposure to benzene and risk of breast cancer: Systematic review and meta-analysis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 831.