"In our study, people with hives showed an increased risk of leukaemia," said Dr. Karin Söderberg, who carried out the research with her colleagues from the Karolinska Institutet, Sweden. "We also found an increased risk of non-Hodgkin's lymphoma among individuals who had eczema during childhood."
However, other allergic conditions such as hay fever, did not appear to increase the risk of suffering from cancer.
The researchers followed 16,539 twins for 31 years and recorded whether they were diagnosed with a blood cancer during that time. These individuals had all answered a questionnaire sent out by the Swedish Twin Registry in 1967, which included questions about allergies.
"An important strength of our study is that the information about allergic conditions was collected prior to the individuals being diagnosed with cancer," said Dr. Söderberg. This prevents the bias that may arise if people, who have already been diagnosed with cancer, are asked to remember whether or not they have ever suffered from an allergy.
The researchers believe that the chronic stimulation of the immune system caused by allergic conditions, which leads to the formation of increased numbers of white blood cells, increases the risk that cancer-causing mutations occur within the white-blood cell population.
"Findings from our study do not support the 'immune surveillance' hypothesis, which stipulates that allergic conditions protect against malignancies by enhancing the ability of the immune system to detect and eliminate malignant cells," they write.
Although childhood eczema appeared to increase the risk that individuals will suffer from non-Hodgkin's lymphoma by around twofold, it is important to realise that the likelihood of any individual suffering from this condition is still remote. Non-Hodgkin's lymphoma only affects 0.03% of people in the USA.
This press release is based on the following article:
Allergic conditions and risk of haematological malignancies in adults: a cohort study
Karin C Söderberg, Lars Hagmar, Judith Schwartzbaum and Maria Feychting
BMC Public Health 2004, 4:51
To be published 4 November 2004
Upon publication, this article will be available free of charge according to BMC Public Health's Open Access policy at: http://www.