Is silicosis required fur silica-associated hung cancer?

Background Abundant epidemiologic and experimental evidence supports the 19 97 International Agency for Research on Cancer classification of crystallin e silica as a human lung carcinogen Nonetheless, there remains uncertainty about whether excessive lung cancer occurs exclusively among workers with s ilicosis. Methods A review was performed of published occupational epidemiologic lite rature directly pertinent to the interrelations among silica exposure, sili cosis, and lung cancer. Results The association between silica and lung cancer is generally but not uniformly, stronger among silicotics than nonsilicotics. However the exist ing literature is ambiguous due to incomplete or biased ascertainment of si licosis, inadequate exposure assessment, and the inherently strong correlat ion between silica exposure and silicosis which hinders efforts to disentan gle unique contributions to lung cancer risk, Conclusions Until more conclusive epidemiologic findings become available, population-based or individually-based risk assessments should treat silico sis and lung cancer as distinct entities whose cause/effect relations are n ot necessarily linked. (C) 2000 Wiley-Liss, Inc.