--In contrast to some earlier reports, allergic conditions appear to increase,
rather than decrease, the risk of leukemia and lymphoma, according to a Swedish
study.
Depending on the root cause of allergies, theories predict that allergic
conditions may either reduce or raise the risk of cancer, researchers explain in
the medical journal BMC Public Health.
While several studies have looked at the allergy-cancer relationship by
comparing people who have cancer to those who do not, there have been few
studies that looked at a representative segment of the general population.
To investigate any connection between allergies and blood cancers, Dr. Karin
C. Soderberg, from the Karolinska Institute in Stockholm, and colleagues
analyzed data from a group of 16,539 Swedish twins who were born between 1886
and 1925.
The presence of allergic conditions was assessed with questionnaires
administered in 1967. The group was followed from 1969 to 1999, and cases of
cancer were identified through the Swedish Cancer Registry.
Analysis of the data indicated that hives and asthma appeared to increase the
risk of leukemia by 2.1- and 1.6-fold, respectively. Similarly, eczema during
childhood was linked to a 2.3-fold higher risk of lymphoma.
As mentioned, the results run counter to past studies, and the team suggests
several possible reasons for the disparity. Perhaps new treatments for allergies
and asthma also affect the chances developing cancer, for example.
Whatever the reason, they point out that it's important to clarify "if and
how" allergic conditions are connected to blood cancers, since the prevalence of
allergies is increasing.
