Asthma and Prostate Cancer
Drake: Good news for men with asthma.
You have a lower risk of prostate cancer, especially the most lethal kind! You may also take comfort in knowing that you have surprised some of Hopkins’ finest investigators.
Scientists have long believed that chronic inflammation of the prostate gland is associated with the development of prostate cancer (for some of the latest exciting work on this, see story). However, the nature of that inflammation is not well-understood. Charles Drake, M.D., Ph.D., Associate Professor of Oncology, Immunology, and Urology, and Co-Director of the Prostate Cancer Multi-Disciplinary Clinic, explains: “This is important because if we could understand the precise immunological mechanisms by which inflammation can promote prostate cancer, it could lead to the development of treatments that dampen chronic prostatic inflammation, or even prevent that inflammation from promoting cancer development.”
Several laboratory studies supported the idea that chronic inflammation that leads to cancer is driven by the presence of a certain family of inflammatory molecules, or cytokines. This family is called the TH2 family, and “interestingly, that same family of cytokines has been shown to be involved in a very common chronic inflammatory condition — asthma,”says Drake. So, Drake hypothesized that men with a history of asthma would have a tendency to develop chronic TH2-mediated inflammation, and would be thus at a greater risk for prostate cancer. Working with colleagues from Harvard, Drake and Elizabeth Platz, Sc.D., M.P.H., Professor of Epidemiology, Oncology, and Urology, tested that hypothesis in 47,880 men participating in the Health Professionals Follow-up Study.
These men were free of the diagnosis of prostate cancer when they enrolled in 1986; just over 9 percent of them had asthma. By 2012, 6,294 of the men were diagnosed with prostate cancer, and of these, 798 were metastatic at diagnosis or during follow-up, or fatal.
“It turned out that men with asthma had a lower risk of prostate cancer, especially lethal prostate cancer.
Surprisingly, they found “the exact opposite result” of the study’s hypothesis,” Drake says. “It turned out that men with asthma had a lower risk of prostate cancer, especially lethal prostate cancer. The association was strongest for fatal prostate cancer; men with asthma had a 36 percent lower risk.”
This surprising result has profound implications for the idea that TH2 inflammation is a contributor to cancer in humans. “One possibility is that the kind of inflammation that drives prostate cancer development is of another sort, possibly TH17 inflammation, which involves very different cytokines,” says Drake. It’s also possible that if the immune system is focused on promoting inflammation in one site, such as the lung, then cancer-promoting inflammation in other sites could be less likely to occur. Finally, “it’s also possible that the mice have been leading us astray, and that TH2-mediated inflammation is not the kind of inflam - mation that leads to cancer in humans .” Drake plans further work in collaboration with pathologist Angelo De Marzo to test for the presence of TH2 inflammation in actual tissue samples.
“These findings are the fruit of a productive collaboration of basic immunology, epidemiology and pathology, and represent the kind of team science that will be important in finding new ways to treat or even prevent prostate cancer.”