From www.bloodjournal.org by guest on February 6, 2015. For personal use only. 2357 CORRESPONDENCE About the Increased Frequency of Acute Promyelocytic Leukemia Among Latinos: The Experience From a Center in Spain To the Editor: Recently, Douer et all found that Latinos with acute myeloid leukemia (AML) have a higher likelihood of the acute promyelocytic leukemia (APL) subtype of disease, whichmay suggest either a genetic predisposition to APL and/or exposure to distinct environmental factor($. The Latino ethnic group was defined in their report based on the origin of the patient: Central and South America, although we assumed that patients from Mexico (North America) were also included in the Latino group. This definition is, in our opinion, based more on cultural features than on racial or even ethnic reasons, because an important mixture of races occurred after the Spanish colonization of America that involved people from the Iberian peninsula, the authoctonous American natives, and, in some areas, black people from Africa. Thus, what was described as the Latino group is an heterogeneous group of races. Nevertheless, we have also found a high incidence of APL in our center in Madrid (Spain) when compared with other regions in North Europe’ or white people from the United States.’ FromJanuary 1986 to December 1994, 104 Spanish patients who were mainly from the region of Madrid were diagnosed as having de novo acute myeloblastic leukemia in our center. Their median age was 47 years (range, 13 to 82 years), and 24 cases corresponded to APL (23%). The rest of the cases were MO (l),M1 (14), M2 (22), M4 (1 l), M5 (25), M6 ( 9 , and M7 (2). Patients with APL were significantly younger, with a median age of 29 years (range, 16 to 59 years) versus 49 years (range, 13 to 82) for those without APL ( P < ,001 t-test). This finding and the increased fre- quency of APL in the Italian population4could favor the hypothesis of a racial predisponition for APL, although other environmental factors cannot be completely excluded. J.F. Tomis J.M. Fernindez-Ratiada Hospital Universitario La Princesa Universidad Autdnoma de Madrid Madrid, Spain REFERENCES 1. Douer D, Preston-Martin S , Chang E, Nichols PW, Watkins KJ, Levine AM: High frequency of acute promyelocytic leukemia among Latinos with acute myeloid leukemia. Blood 87:308, 1996 2. Cantti-Rajnoldi A, Biondi A, Jankovic M, Masera G , Rovelli A, Uderzo C, Head D, Raimondi S , Creutzig U, Ritter J: Diagnosis and incidence of acute promyelocytic leukemia (FAB M3 and M3 variant) in chilhood. Blood 81:2209, 1993 3. Steuber CP, Civin C, Krischer J, Culbert S , Ragab A, Ruymann FB, Ravindranath Y, Leventhal B, Wikinson R, Viett TJ: A comparison of induction and manteinance therapy for acute non-lymphocytic leukemia in childhood: Results of a pediatric oncology group study. J Clin Oncol 9:247, 1991 4. Biondi A, Rovelli A, Cantu-Rajnoldi A, Fenu S , Basso G , Lucian0 A, Rondelli R, Mandelli F, Masera G , Testi AM: Acute promyelocytic leukemia in children: Experience of theItalian Pediatric Hematology and Oncology Group (AIEOP). Leukemia 8:1264, 1994 From www.bloodjournal.org by guest on February 6, 2015. For personal use only. 2358 CORRESPONDENCE Response AsDrs Thomas and Fernandez-Raiiada correctly comment, we defined Latinos as people originating in Central and South America and Mexico. We agree that the genetic background of these populationsisindeed heterogenous and includes ancestors from Europe, different American Indian tribes, and other races. The patient populations that we studied were notlarge enough to examine more homogenous Latino subgroups for the frequency of APL. Whether the high frequency of APL seen in Los Angeles County relates to place of residence before diagnosis of APL, to dietary or life style habits, or to a specific genetic background isasyet undetermined. Weare currently beginning an international study involving patient populations from the United States, Mexico, and Argentina in an attempt to address the specific issue of Latino subpopulations. As referred to in our report, a higher than expected frequency of APL has also been noted in a series of AML patients from different countries in Central and South America"' and Italy'.' and the information provided in the letter of Drs Thomas and Femindez-RaRada extends this observation to AML patients in Spain. However, it is important to recognize several potential biases in studying the frequency of APL among AML patients. Thus, data from hospitals could be biased by distinct referral patterns. For example, APL is a disease of younger adults, whereas other AML subtypes are more common in older patients. Referral of elderly patients with AML to a hospital for intensive treatment could be lowerbecause of an expected poor outcome. This could favor a higher rate ofhospitalization of APL cases than other AML patients and could artificially increase the proportion of APL. In addition, careful pathologic verification of non-APL cases is extremely important. The morphologic criteria for APL are themost specific, sensitive, and reliable of all French-American-British (FAB) subtypes.(' Howevernon-APL cases, in particular FAB subtypes MO and M I , if erroneously misclassified, are more likely to be defined as acute lymphoblastic leukemia rather than APL. In that case. the number of non-APL cases and the total number of AML cases would decrease, resulting in a spurious increase in the proportion of APL among AML cases. Our study tried tominimize these biases by comparing Latinos with nonLatinos, by adjusting the risk of APL for age, and by using population-based data with central pathologic subgroup verification of all AML cases. We believe that our conclusion that APL is more frequent in Latinos with AML is valid. The observation of Drs Thomas and FernLndez-Raiiada and other similar reports point to the same conclusion, ie, that APL may have an uneven geographic or ethnic distribution and that APL may be more frequent inAML patients in certain population groups that are categorized as Latinos. Further research on the epidemiology of AML must be subgroup-specific. Dan Douer Alexandra M. Levine Division of Hematology Department of Medicine Susan Preston-Martin Department of Preventive Medicine Peter W. Nichols Department of Pathology The Norris Comprehensive Cancer Center University of Southern California Los Angeles, CA REFERENCES 1. Malta-Corea M, Pacheco-Espinoza C, Cad-Rajnoldi A, Conter V, Lietti G, Masera G, Sessa C, Cavalli F, Biondi A, Rovelli A: Childhood acute promyelocytic leukemia in Nicaragua. Ann Oncol 42392, 1993 2. Loureiro P, Azevedo A, Maia A, Freire AD, Souto F, Bandeira F, Vasconcelos J, Paiva A: Acute myeloid leukemia: Presentation of the disease and response to treatment in Northeast of Brazil. Med Pediatr Oncol 20:439, 1992 (abstr) 3. De Salvo L, Weir-Medina J, Gomez-Sanchez 0, de Baena ES, de Ramos BU, Guevara J, Leungo Vera J, de Vizcaino MA, Sanchez H, de Leon E: Leucemia promielocitica aguda en el occidente de Venezuela. Sangre 34:329, 1989 4. Canth-Rajnoldi A, Biondi A, Jankovic M, Masera G, Rovelli A, Uderzo C, Head D, Raimondi S, Creutzig U, Ritter J: Diagnosis and incidence of acute promyelocytic leukemia (FAB M3 and M3 Variant) in childhood. Blood 81:2209, 1993 5. Biondi A, Rovelli A, Cantu-Rajnoldi A, Fenu S, Basso G, Luciano A, Rondelli R, Mandelli F, Masera G , Testi AM: Acute promyelocytic leukemia in children: Experience of the Italian Pediatric Hematology and Oncology Group (AIEOP). Leukemia 8:1264, 1994 6. Bennett JM, Catovsky D, Daniel MT, Flandrin G, Galton AG, Gralnick HR, Sultan C: Proposed revised criteria for the classification of acute myeloid leukemia. Ann Intern Med 103:626, 1985 From www.bloodjournal.org by guest on February 6, 2015. For personal use only. 1996 88: 2357-2358 About the increased frequency of acute promyelocytic leukemia among Latinos: the experience from a center in Spain [letter; comment] JF Tomas and JM Fernandez-Ranada Updated information and services can be found at: http://www.bloodjournal.org/content/88/6/2357.citation.full.html Articles on similar topics can be found in the following Blood collections Information about reproducing this article in parts or in its entirety may be found online at: http://www.bloodjournal.org/site/misc/rights.xhtml#repub_requests Information about ordering reprints may be found online at: http://www.bloodjournal.org/site/misc/rights.xhtml#reprints Information about subscriptions and ASH membership may be found online at: http://www.bloodjournal.org/site/subscriptions/index.xhtml Blood (print ISSN 0006-4971, online ISSN 1528-0020), is published weekly by the American Society of Hematology, 2021 L St, NW, Suite 900, Washington DC 20036. 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