Women with airborne allergies - particularly in relation to plants, grass and trees - may be at higher risk of blood cancer than others, a recent study has revealed.
While investigating the association of chronic immune stimulation and development of hematologic (blood) cancers, scientists found that gender may have an important role to play.
"To the best of our knowledge, ours is the first study to suggest important gender differences in the association between allergies and hematologic malignancies," wrote Mazyar Shadman, the study's first author.
According to Shadman, who led the research, the immune system's potential role in cancer causation is a focus of intense scientific interest.
"If your immune system is over-reactive, then you have problems; if it's under-reactive, you're going to have problems. Increasing evidence indicates that disregulation of the immune system, such as you find in allergic and autoimmune disorders, can affect survival of cells in developing tumours."
The study drew on a large sample of people aged 56-70 and included a questionnaire that focused on three areas: health history and cancer risk factors, medication and supplement use, and diet.
History of asthma and allergies was also taken, including allergies to plants, grasses or trees; mould or dust; cats, dogs or other animals; insect bites or stings; foods; and medications.
The 66,000 participants were followed for a median of eight years until they withdrew from the study, moved away, had a cancer diagnosis other than hematologic malignancy or non-melanoma skin cancer, or died.
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When stratified by gender, the incidence of blood cancers in response to these allergens was increased in women but not in men. The reason for this is as yet unknown, although authors suggest that investigating the hormonal effects on the immune system may offer an alternative explanation.
"Given the limited number of cases within each subtype of hematologic cancer, the risk estimates need to be interpreted with caution … and the possibility of chance finding due to multiple testing should be recognized," Shadman and colleagues wrote.
The findings are published in the December print issue of the American Journal of Hematology.