Men with asthma less likely to develop lethal prostate cancer

In what they are calling a surprising finding in a large study of men who completed questionnaires and allowed scientists to review their medical records, Johns Hopkins researchers report that men with a history of asthma were less likely than those without it to develop lethal prostate cancer.

In their analysis of data collected from 47,880 men and described online Feb. 27 in the International Journal of Cancer, the scientists found that men with a history of asthma were 29 percent less likely to have been diagnosed with prostate cancer that spread or to have died of their prostate cancer. Overall, asthmatic men were 36 percent less likely to die of the disease.

The findings are particularly surprising, because some studies suggested that prostate cancer is linked to the kind of inflammation associated with asthma, which itself is a chronic inflammatory condition, says Elizabeth A. Platz, Sc.D., M.P.H., a professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health and co-leader of the Cancer Prevention and Control Program at the Johns Hopkins Kimmel Cancer Center.

Platz strongly cautioned, however, that it's not possible from the study to say that asthma protects men from prostate cancer.

"We don't know yet whether the association we see in this observational study is a case of cause and effect," she says.

The analysis suggested that men with asthma had a lower risk of developing lethal prostate cancer even when researchers considered such factors as whether the men took medication for asthma or whether their asthma was diagnosed early or later in life.

The researchers also analyzed links between a history of hay fever and lethal prostate cancer, finding a smaller but opposite association: Men with hay fever were 10 to 12 percent more likely to have lethal or fatal prostate cancer.

The 47,880 men ages 40 to 75 participated in Harvard's Health Professionals Follow-Up Study from 1986 through 2012 and did not have a cancer diagnosis before 1986. Study participants had completed a questionnaire every two years, reporting on demographic information, medical history, medication use and lifestyle factors. For men who reported a prostate cancer diagnosis, researchers evaluated their medical records and pathology reports. Among them, 9.2 percent reported a diagnosis of asthma, while 25.3 percent had been diagnosed with hay fever. There were 798 confirmed lethal prostate cancer cases in the group.

Platz and Charles Drake, M.D., Ph.D., co-director of the Prostate Cancer Multidisciplinary Clinic at the Johns Hopkins Kimmel Cancer Center, began looking at a possible connection between asthma and prostate cancer based on work in mice showing that the immune cells that infiltrate prostate tumors produce an immune response known as Th2 inflammation.

"Asthma is often considered to be a disease of chronic inflammation, particularly Th2 inflammation," Drake explains. ""