Lung Cancer: Allergic Disease History Might Decrease Risk

Mariam El-Zein, PhD. Associée de recherche/ Research associate Unité d'épidémiologie et biostatistique / Epidemiology & Biostatistics Unit INRS-Institut Armand-Frappier Université du Qué Interview with:
Mariam El-Zein, PhD.
Associée de recherche/ Research associate
Unité d’épidémiologie et biostatistique / Epidemiology & Biostatistics Unit
INRS-Institut Armand-Frappier
Université du Québec What are the main findings of the study?

Answer: The overall indication is that a prior history of allergic diseases (asthma, eczema or hay fever) might decrease lung cancer risk. There was a 36% (odds ratio= 0.64, 95% confidence intervals: 0.44-0.93) reduction in lung cancer risk among subjects who reported a history of asthma. Hay fever was associated with a 67% (odds ratio= 0.33, 95% confidence intervals: 0.19-0.59) reduction in lung cancer risk. Smoking was accounted for using a comprehensive smoking index that takes into account multiple dimensions of smoking behaviour (i.e., smoking status, intensity, duration, and time since cessation). A lower risk of lung cancer (reduction by 37%; odds ratio= 0.63, 95% confidence intervals: 0.38-1.07) was found among those having had eczema, but was not statistically significant. Were any of the findings unexpected?

Answer: On the one hand and from a clinical point of view, we were not expecting a strong association between eczema and lung cancer, as eczema is not connected with the airways. Also, the strongest associations found with hay fever are hard to explain clinically since allergic rhinitis is not expected to affect the lower respiratory tract. On the other hand, we had hypothesized a consistent risk pattern across all three allergic diseases if a common biological mechanism were to be involved. What should clinicians and patients take away from your report?

Answer: The findings from our study should be considered within the context of current epidemiological evidence of a relation between allergic diseases and lung cancer risk, which is still controversial. Our findings do not necessarily inform us on public health strategies or recommendations to make for lung cancer prevention, but rather calls for further research on possible mechanisms of immunostimulation, specifically that of the immune surveillance hypothesis which suggests that a hyper-reactive immune system is more efficient for tumor recognition and elimination. What recommendations do you have for future research as a result of this study?

Answer: Our population-based study considered incident and histologically confirmed lung cancer cases, and we had detailed information on multiple covariates, including smoking, which are critical aspects in a sound epidemiological study. Yet, our study, as well as all previous studies, relied on self-reported allergic diseases. It would thus be pertinent to consider immunological markers in the ascertainment of allergic diseases in cohort studies. As well, the interpretation of our findings, and those of other researchers, relies on the eventual elucidation of underlying molecular and immunological mechanisms, which should be the focus of future research.


History of allergic diseases and lung cancer risk

Mariam El-Zein, PhD1 Marie-Elise Parent, PhD1,2,3 Jack Siemiatycki, PhD2,3 Marie-Claude Rousseau, PhD1,2,3*

1 INRS-Institut Armand-Frappier, Université du Québec, Laval, Québec, Canada

2 Department of Social and Preventive Medicine, University of Montreal, Montréal, Québec, Canada

3 University of Montreal Hospital Research Centre (CRCHUM), Montréal, Québec, Canada
Annals of Allergy, Asthma & Immunology – 17 January 2014 (10.1016/j.anai.2013.12.021)