Allergy link to blood cancer risk

Eczema was linked to a form of lymphoma

Some allergic conditions may increase the risk of developing blood cancer as an adult, research suggests.

Scientists found people with hives had an increased risk of leukaemia, while those who had childhood eczema were at higher risk of non-Hodgkin's lymphoma.

The research, by Sweden's Karolinska Institute, is published in the journal BMC Public Health.

UK experts have questioned whether the findings are robust, and advised people with allergies not to be alarmed.

The interpretations of the results of this study are questionable. Hazel Nunn

Other allergic conditions, such as hay fever, did not appear to increase risk of cancer.

The researchers followed 16,539 twins for 31 years and recorded whether they were diagnosed with a blood cancer during that time.

All the people who took part in the study had answered a questionnaire sent out by the Swedish Twin Registry in 1967, which included questions about allergies.

Researcher Dr Karin Söderberg said: "An important strength of our study is that the information about allergic conditions was collected prior to the individuals being diagnosed with cancer.

"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."

Stimulation

The researchers believe the key may be chronic stimulation of the immune system caused by allergic conditions.

This leads to the formation of increased numbers of white blood cells, increasing the risk that cancer-causing mutations occur within the white-blood cell population.

Some experts believe that allergic conditions might actually protect against cancer by enhancing the ability of the immune system to detect and eliminate malignant cells.

But the Karolinska team said their findings suggest there is little truth in this hypothesis.

They stress that although childhood eczema appeared to increase the risk that individuals will suffer from non-Hodgkin's lymphoma by around two-fold, it was important to realise the likelihood of any individual suffering from this condition is still remote.

Hazel Nunn, of the charity Cancer Research UK, said: "Although some aspects of this study are well designed we must be careful when interpreting the results.

"They do not show a convincing link between allergies and blood cancers.

"The interpretations of the results of this study are questionable because the apparent link between allergies and cancer that have been identified are most likely to be due to chance.

"This is an area where further research is welcomed and allergy sufferers should not be alarmed."