An Ecologic Perspective of Multiple Myeloma Incidence: Heterogeneous Effects of Industrial Exposures and Socioeconimic Status

Purpose The etiology of multiple myeloma is unclear. Low case numbers often limit myeloma epidemiologic investigations and an ecologic approach may provide an opportunity to generate hypotheses. We investigated the effect of the industrial presence on the rate of myeloma using aggregate data from Arkansas. Methods Overall, racially-stratified (African-American and Caucasian), and gender-stratified age-adjusted MM incidence rates from 1998-2004 were obtained for all Arkansas counties and incorporated as continuous variables. Information regarding the industrial presence was obtained from 1998–2004 County Business Pattern data. Rate ratios (RRs) for the effect of industrial presence on myeloma were estimated for each industry using Poisson regression for overall and population-specific models. Results Areas with paper mills had RRs consistently higher than areas without paper mills for both racial subgroups, but the estimates were 3-fold greater for African-Americans (RR=4.65, 95%CI=0.51, 42.5) than Caucasians (RR=1.46, 95%CI=0.96, 2.23). Areas with wood-related exposures demonstrated higher RRs for females than males. Areas with persistent poverty had elevated RRs for African-Americans (RR=3.09, 95%CI=0.89, 10.8) and males (RR=1.48, 95%CI=1.19, 1.85), but were slightly protective for Caucasians (RR=0.93, 95%CI=0.69, 1.24) and females (RR=0.82, 95%CI=0.60, 1.12). Conclusion Several industries demonstrated qualitative differences for myeloma incidence by race and gender. Future investigations of industrial presence and myeloma should consider potential effect modification by race and gender.