Multiple myeloma and family history of cancer among blacks and whites in the U.S.

BACKGROUND. In the U.S., the incidence rate of multiple myeloma is more than twice as high for blacks as for whites, but the etiology of this malignancy is not well understood. METHODS. A population-based case-control interview study of 565 subjects (361 white, 204 black) with multiple myeloma and 2104 controls (1150 white, 954 black) living in 3 areas of the U.S. offered the opportunity to explore whether family history of cancer contributes to the risk of multiple myeloma and explains the racial disparity in risk. RESULTS. For both races combined, the risk of multiple myeloma was significantly elevated for subjects who reported that a first-degree relative had multiple myeloma (odds ratio [OR] = 3.7, 95% confidence interval [CI] = 1.2-12.0). Increased risk was also associated with a family history of any hematolymphoproliferative (HLP) cancer (OR = 1.7, 95% CI = 1.0-2.8), especially in a sibling (OR = 2.3, 95% CI = 1.1-4.5]. The risk associated with familial occurrence of HLP cancer was higher for blacks than for whites, but the difference between the ORs was not statistically significant. CONCLUSIONS. These data are consistent with previous studies that indicate a familial risk of multiple myeloma, but they explain little of the race- related difference in incidence rates.