Objective: To describe the risk patterns of multiple myeloma in Los Angeles County (LAC).
Methods: Incident multiple myeloma cases diagnosed from 1972 to 1999 were ascertained by the population-based cancer registry for LAC. Average annual age-specific and age-adjusted incidence rates (AAIR), standardized to the 2000 US census age distribution, were calculated using age-, race-, sex- and socioeconomic status (SES)-specific denominators estimated for all years from US census data for 1970, 1980 and 1990. Odds ratios (ORs) for risk by birthplace and religion were estimated using multivariate logistic regression, comparing multiple myeloma patients with other cancer patients.
Results: All groups experienced increasing incidence with age; African-Americans experienced the steepest increase which began a decade earlier compared to other groups. Overall incidence rates were 50% higher among males (n = 4,692) than females (n = 4,343) (p < 0.05). AAIRs were highest for African-Americans, followed by Spanish-surnamed whites (SSW), non-Spanish-surnamed whites (NSSW), Filipinos and other Asian groups. Among African-Americans, incidence rates increased with increasing SES. US-born SSW had 14% lower risk compared to non-US born SSW (OR = 0.86, 95% confidence interval [CI] = 0.74-0.99]. Jews had an 11% higher risk compared to Protestants (OR = 1.11; 95% CI = 0.99-1.24).
Conclusion: Risk patterns suggest a role for both environmental and genetic factors.