SEASONAL CLUSTERING OF ADULT ACUTE LEUKEMIAS IN A SUB-TROPICAL AREA OF BRAZIL
Author(s): ,
Irene Lorand-Metze
Affiliations:
Internal Medicine,University of Campinas,Campinas,Brazil;Hematology/Hemotherapy Center,University of Campinas,Campinas,Brazil
,
Rosana AT Pereira
Affiliations:
Pathology,University of Campinas,Campinas,Brazil
,
Kátia B Pagnano
Affiliations:
Hematology/Hemotherapy Center,University of Campinas,Campinas,Brazil
Konradin Metze
Affiliations:
Pathology,University of Campinas,Campinas,Brazil
EHA Library. Lorand-Metze I. 06/09/16; 134512; PB1612
Prof. Dr. Irene Lorand-Metze
Prof. Dr. Irene Lorand-Metze
Contributions
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Abstract
Abstract: PB1612

Type: Publication Only

Background
 Seasonal peaks in the diagnosis of acute leukemias have been reported in different countries all over the world. These peaks may be caused by temporal changes in environmental factors (pollutant agents, allergens, pathogens) or by the known seasonal changes in the human immune system. Particularly, childhood acute lymphoblastic leukemia (ALL) has been studied, but results are inconsistent. Winter peaks have been found in Sweden, Finland, Iran, and South Africa, but a summer peak has been described in England. Brazil is a large country with latitudes ranging from the equator to sub-tropical areas. The Tropic of Capricorn passes near the city of São Paulo. So, the state of São Paulo has a hot and rainy summer, and a dry winter with days of low temperatures in the night.

Aims
We examined the seasonal trends in adult acute leukemia in our region analyzing the relation between the number of newly diagnosed cases of ALL and AML per month and maximum and minimum temperatures, as well as pluvimetric data  during the last 25 years. 

Methods
We examined the monthly number of newly diagnosed cases of AML and ALL (age < 18 years) and its relation to monthly maximal, minimal and median temperatures as well as the amount of rainfall.

Results
 During this period, 1303 AMLs and 236 ALLs entered the study. Concerning ALL, there was a significant positive correlation between the absolute minimum monthly temperature, the pluviometric index of the month of diagnosis, as well as these features in the 3 previous months. In a multiple regression analysis, only the pluvimetric index of the month before diagnosis entered into the final model (r = 0.177;p = 0.001). Concerning AML, there was a significant positive correlation (r = 0.12;p = 0.01) only with the absolute maximum  temperature of the month of diagnosis. None of the other variables examined were found to be significant.

Conclusion
We observed a seasonal variation in the diagnosis of adult ALL related to temperature and especially to rainfall in the months preceding the diagnosis. This may be associated with a higher incidence of environmental allergens or infections in the more humid months of the year, leading to the outbreak of the disease, as has also been postulated for childhood and adult ALL in other countries. Concerning AML, a clear relation was found only with actual high temperature peaks. Perhaps, the temperature stress could provoke decompensation of an already existing bone marrow failure making the patients seek for medical assistance. This does not exclude that other environmental factors related to the pathogenesis of AML may act with different intensities in different climatic conditions.

Session topic: E-poster

Keyword(s): Acute lymphoblastic leukemia, Acute myeloid leukemia, Diagnosis, Epidemiology

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