Besides the known factors such as the presence of oncogenes, the macro-environment (pollution, infections) or organic microenvironment (dysregulation of the immune system) can be the triggering factor of the process of leukemogenesis. It is known that the amount of rainfall can affect the distribution (dilution) of pollutants in the air and water reserves. There is no description of the climate influence in the incidence of Acute Promyelocytic Leukemia (APL), which has its own clinical laboratory characteristics, and is defined by the presence of the PML-RARA rearrangement.

The aim of this study was to investigate the impact of seasonality in the incidence of Promyelocytic Leukemia in Brazil, and its characteristics.

Patients and methods

we analyzed the clinical laboratory data and origin of participant cases of the International Consortium on Acute Promyelocytic Leukemia (IC-APL), a group multicenter treatment of APL with standardized diagnosis and treatment. We included all patients diagnosed with APL of Brazilian centers between 2006 and 2011. We excluded patients without demographics. Patients were divided into macro-climate (Northeast, South and Southeast). Northeast: 49 cases of Pernambuco, Southeast: 16 cases of Minas Gerais, São Paulo 88 cases; South: 27 cases of Rio Grande do Sul and 19 cases of Paraná. Meteorological data were extracted from the database Meteorological Research and Education (BDMEP) of the National Institute of Meteorology (INMET), and grouped by quarter. We studied the mean maximum temperature, mean minimum temperature and rainfall. The relationship between the number of cases and meteorological data were analyzed by the Spearman test.

Results

We included 149 patients with APL. In the South, there were 46 patients, 50% female and 50% male, mean age: 37 years, 16 cases occurred on the first quarter (January-March), 12 on the second quarter (April-June), 8 cases on third quarter (July-September) and 10 on the fourth quarter (October to December). In the Northeast, there were 49 cases, 25 female and 24 male, mean age 34 years with 11 cases on the first and second quarters, 12 cases on the third quarter and 15 cases on the fourth quarter. Southeast: 54 cases with 29 female cases and 25 male cases, mean age 25 years, with 12 cases on the first and second quarter, 11 cases on the third quarter and 19 cases on the fourth quarter. In the South, there was no statistically significant correlation between the weather and the number of registered cases of APL. In the Northeast, there was a negative correlation between the number of cases of APL and rainfall (r = -0.57, p = 0.004) and a trend with the maximum temperature (r = 0.34, p = .07). In the southeast, there was positive correlation between rainfall (r = 0.42, p = 0.02) but not with temperature. In the northeast, the smallest amount of rainfall is associated with higher temperatures (r = -0.49, p <0.0002), whereas in the Southeast, the greater amount of rainfall is associated with warmer temperatures.

Conclusion

There is no known etiology of APL, but the correlations found between rainfall and number of cases could be related to the dispersion of pollutants into the environment.

Disclosures:

No relevant conflicts of interest to declare.

Topics:
acute promyelocytic leukemia, brazil, seasonal variation, dilution technique, infections, leukemogenesis, progressive multifocal leukoencephalopathy, retinoic acid receptor alpha, dilute (action), immune system

Author notes

*

Asterisk with author names denotes non-ASH members.

© 2013 by The American Society of Hematology
2013
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