A study on acute myeloid leukemia (AML) resulting from an international collaboration led by the Fundación Jiménez Díaz, with the participation of the University of Bristol (United Kingdom) has shown that in January there is an increase in their diagnosis.
The idea of carrying out this research arose from the hypothesis defended by several hematologists that diagnosed cases of AML tend to occur in clusters. “For this reason, we decided to evaluate the temporal distribution of diagnosed cases of AML in Spain between the years 2004-2015,” he explains. Juan Manuel Alonso Dominguezone of the main authors of the work published in the British Journal of Haematology.
The objective of the study was to investigate the temporal pattern of the diagnosis of cases of acute myeloid leukemia in the general population and by age and sex strata. In this way, a temporal aggregation was found in the diagnosis of this type of leukemia that “could indicate the existence of a seasonal etiological factor that would explain this temporal association”, explains Fernando Sánchez-Vizcaíno, from the University of Bristol and first signatory of the study.
To carry out the research, anonymous data from patients admitted to Spanish hospitals with acute myeloid leukemia between 2004 and 2015, obtained from the Ministry of Health, were used. In addition, the population at risk was estimated from the census registered by the National Institute of Statistics in the same period. “The monthly incidence of AML was derived for the study period, which was analyzed through multivariable generalized linear Poisson models, which take into account the temporal dependence of the observations by introducing autoregressive and moving average components,” he explains. Sánchez-Vizcaíno, adding that 26,472 cases were analyzed, which was “the largest series of cases of acute myeloid leukemia ever analyzed for this purpose.”
Seasonal risk factors influence AML
According to the results, in January the incidence of AML cases increases, “with a minimum average difference of 7 percent when compared to February, and with a maximum average difference of 16 percent when compared to November and August,” he details. Sanchez-Vizcaino. The fact that the diagnosis of acute myeloid leukemia is seasonal iIt would imply that seasonal risk factors, such as infectious or environmental agents, influence the development and/or proliferation of the disease.
“Our results showed an annual peak, which would be more consistent with exposure to a viral agent than with exposure to an environmental factor,” says Alonso. In this order, he continues «the etiological mechanism should be different from that exerted by chronic viral pressure, since it is an aggressive and acute disease that probably requires a short incubation period. The alternative and more plausible mechanism would be that a viral agent stimulates the rapid proliferation of pre-existing and quiescent leukemic stem cells”, he explains.
The results open new lines of research to determine the association between potential seasonal risk factors and the disease
The results make it necessary to carry out complementary epidemiological studies to investigate the association between seasonal risk factors and the increase in cases of acute myeloid leukemia in winter. Likewise. Alonso indicates that “there is a widely accepted theory in the scientific community that postulates that AML and other tumors are produced from a tumor stem cell, which would have to be eliminated to eradicate the tumor.
Other lines of research
With the treatments, most of the tumor is eliminated, but these stem cells are not usually eradicated, giving rise to relapses”, so “clarifying how the virus triggers the replication of the leukemic stem cell could help unravel the mechanisms of regulation of the quiescence of stem cells”, say the scientists.
The results showed an annual peak, more consistent with exposure to a viral agent than with exposure to an environmental factor.
The authors explain that, in order to continue this line of research, the first step is to obtain the necessary funding to be able to carry out the complex experiments described above. To do this, we are forming a network of collaborators with other leading international research groups in their respective disciplines to jointly apply for national and European public research grants. “We are also in the process of establishing contact with various private companies to explore with them new opportunities for collaboration in the development of our scientific aspirations,” conclude doctors Alonso and Sánchez-Vizcaíno.
Leukemia is a type of cancer that occurs in the bone marrow and is classified, according to the affected hematopoietic line, into lymphoid (if lymphocytes are affected) and myeloid (when it occurs in any other blood element); and, depending on its speed of progression, in acute or chronic.