One theory posited by the authors of a new study is that asthma patients may have an enhanced propensity for a CD4+ T-cell helper response.
In a seemingly contradictory finding, men with asthma appear to be less likely to suffer from aggressive prostate cancer or to die from the disease, according to a large, prospective cohort study.
“Men who were ever diagnosed with asthma were less likely to develop lethal and fatal prostate cancer,” noted the researchers, led by Elizabeth A. Platz, Sc.D, Professor of Epidemiology at the Johns Hopkins Bloomberg School of Public Health in Baltimore, MD.
Inflammation, and more generally, the immune response are thought to influence the development of prostate cancer. To determine the components of the immune response that potentially contribute to prostate cancer, Platz and colleagues prospectively evaluated the association of immune-mediated conditions, asthma, and hay fever with lethal prostate cancer risk in the Health Professionals Follow-up Study.
They included 47,880 men aged 40 to 75 years with no prior cancer diagnosis. The men answered a baseline questionnaire in 1986, reporting diagnoses of asthma and hay fever and the year of onset. On follow-up questionnaires, the men answered questions on demographics, medical history, and lifestyle factors at regular yearly intervals, and reported new asthma and prostate cancer diagnoses.
If a man reported a prostate cancer diagnosis on a questionnaire, the researchers examined his medical records and pathology reports.
In total, 9.2% of the men reported they had been diagnosed with asthma. One-quarter of them reported having a hay fever diagnosis at baseline.
During 995,176 person-years of follow-up by 2012, the researchers confirmed 6,294 cases of incident prostate cancer and 798 lethal prostate cancer cases. The lethal prostate cancer diagnoses included distant metastases, progression to distant metastasis, and deaths (625 cases) as a result of prostate cancer.
A regression analysis, adjusting for known prostate cancer risk factors such as age, race, body mass index, and smoking, revealed that those men who had a diagnosis of asthma were at higher risk of a lethal prostate cancer (RR = 0.71) as well as a higher risk of fatal disease (RR = 0.64).
At baseline, 2,516 men (5.3%) had a history of asthma, and an additional 1,906 men were diagnosed with asthma during follow-up. “Hay fever with onset in the distant past was possibly weakly positively associated with risk of lethal (RR = 1.10) and fatal (RR = 1.12) disease,” they reported.
In conclusion, the research stated that “our findings may lead to testable hypotheses about specific immune profiles in the etiology of lethal prostate cancer.”
Those hypotheses involve chronic inflammation and the pathogenesis of prostate cancer and the association with more aggressive disease. An immune response linked to asthma may result in large numbers of circulating eosinophil cells. Another possibility is that asthma patients may have a genetic or environmental propensity for a CD4+ T-cell helper response.
The researchers published their results in the Feb 3, 2015 issue of the International Journal of Cancer.
Platz EAm Drake CG, Wilson KM, et al. Asthma and risk of lethal prostate cancer in the Health Professionals Follow-Up Study. Internat J Cancer. Article first published online: 27 FEB 2015. DOI: 10.1002/ijc.29463. http://onlinelibrary.wiley.com/doi/10.1002/ijc.29463/full