Explaining the Excess Risk of Multiple Myeloma in African-Americans

Abstract 4002

African-Americans (AA) have a 2–3-fold higher risk of multiple myeloma (MM) relative to Whites (Gebregziabher, 2006). We have formed a consortium and are conducting a multi-center study with 9 clinical centers and 4 NCI Surveillance, Epidemiology and End-Results (SEER) Program population-based cancer registries to determine the causes of the disease in this population and explain the excess risk (Myeloma in African-American Patients, MAP). Participation involves providing a blood or saliva specimen for DNA and answering a lifestyle and medical history questionnaire. At the end of the data collection period, a genome-wide scan will be performed and our results compared to those from 2,000 African-American controls participating in cohort studies. Patients with African ancestry (predominantly African-Americans) are identified from outpatient clinic rosters or from population-based cancer registries. For patients recruited at clinics, information on subtype, cytogenetics, FISH and lytic bone lesions is abstracted from medical records. To date, 601 patients have agreed to be in the study and we have received DNA samples from 592 patients; 54.6% are female and 45.4% are male. The mean age at diagnosis is 57 years (SD =11.2) with a median age at diagnosis of 58 years (range 27 to 90 years of age). Of the 514 subjects who completed a questionnaire, 7.8% were obese at age 20 (body mass index > 30) and 39% were obese 5 years prior to diagnosis. A first-degree relative with MM was reported by 17 cases (3%), 74% higher than the lifetime risk of 1.7% in the general population based on SEER data. In addition, cases reported 21 first-degree relatives with leukemia (4%), 7 with non-Hodgkin lymphoma (1%) and 14 with Hodgkin lymphoma (3%). To date, clinical information has been abstracted for 351 patients. Of these, 207 (58%) have active disease with the following distribution: stage I (30%), stage II (27%) and stage III (43%). The remainder have relapsed (13%), refractory (1%), relapsed and refractory (4%), or smoldering myeloma (6%), or are in remission (18%). The subtype distribution is: IgG (74%), IgA (11.4%), IgD (0.9%) and IgM (0.3%), and light chain only (13.5%); a distribution significantly different from that observed in a predominantly White population (P <0.007) (Kyle, 2003), (Table 1). Lytic bone lesions were present in 67% of patients, similar to the prevalence observed in other series. FISH and cytogenetics data on hyperdiploidy, deletions in chromosome 13 and 17p, and IGH translocations are being collected on this large cohort of African-Americans patients and will be presented at the ASH meeting. Disease characteristics in AA patients appear to be different than those previously reported in predominantly White populations.