Elucidating disparities across racial and ethnic groups in multiple myeloma patients.

Several studies have established trends in the prevalence and incidence of multiple myeloma (MM) across races. Kaya et al. [1] recently shared findings using data from the Surveillance, Epidemiology, and End Results (SEER) program that not only confirm some of these trends, but also introduce data for demographics not previously studied in-depth. One notable finding is the improved overall survival (OS) of MM patients of Asian/Pacific Islander background. Previously, assessment of this demographic has been difficult, due to the low incidence rate of MM in this population. Studies show that the prevalence of monoclonal gammopathy of undetermined significance (MGUS), the precursor lesion of MM, is low in persons of Asian/Pacific Islander origin [2–4]. The bulk of literature addressing disparities in MM has focused on examining the clinical and biological differences in MM between blacks and whites; little has been done on Asian/Pacific Islanders, so we commend the authors on beginning to find answers in an under-studied population. Although no differences were seen in OS between blacks and whites, these findings may be confounded by different effects over time. Was there a difference between blacks and whites in the most recent decade (1993–2003)? It would be particularly useful if we had data on OS between blacks and whites in the more recent 10-year period, e.g., 2000–2010, because there is a suggestion that blacks have better survival than whites with the arrival of lenalidomide [5]. There is also a need to examine differences in clinical presentation between Asian/Pacific Islanders, whites, and blacks. We believe that results of such studies would provide insight into the biological mechanisms underlying these differences in incidence and survival; additionally, the same needs to be done for MGUS for all races and ethnicities [6, 7]. There are differences in immunoglobulin heavy chain type as well as free light chain ratio distributions in blacks and whites that are associated with risk level of disease found in the population [8]; perhaps investigation of such factors could help to explain the improved OS of Asian/Pacific Islanders. Of additional interest would be an examination of how related B-cell malignancies (Waldenstrom’s macroglobulinemia, amyloidosis, chronic lymphocytic leukemia, etc.) behave in this particular population; i.e., do they cluster in families, as they do in whites, and is there any difference in incidence of these related conditions between Asian/Pacific Islanders and whites. Answers to such questions could help to inform clinical practice and monitoring of relatives of patients. Additionally, Kaya et al. report a worse OS for individuals of American Indian/Alaskan native backgrounds. As the authors point out, it is known that there is disparity in access to healthcare and in health education between whites in the US and American Indians/Alaskan Natives [9, 10]; however, as with Asian/Pacific Islanders, clinical and biological characteristics related to MM need to be examined in order to discern whether the disparity is due primarily to access to healthcare or due to an increased biological predisposition to development of MM so that appropriate measures can be taken. Additionally, to our knowledge, MGUS has never been examined in this population; this would be of great interest as well. The true A. J. Greenberg Division of Epidemiology, Department of Health Sciences Research, Mayo Clinic, Rochester, USA