Spread of breast cancer to lungs in asthma patients may be prevented by use of common inhalers

Monday, April 23, 2007

SCOTTSDALE, Ariz. — An intriguing study conducted by researchers at Mayo Clinic in Arizona suggests there may be a link between asthma and the spread of cancer in breast cancer patients. Importantly, using available inhaler medications could reduce potential metastasis to the lungs in breast cancer patients who have asthma.

"A link between pulmonary inflammation and lung metastasis would not only have significant effects on patient diagnosis and care, but may also immediately affect the way breast cancer patients are treated," said Anna Taranova, M.D., senior research fellow at Mayo. "Those with asthma might be able to reduce their risk of lung metastasis - and increase their survival - with aggressive use of currently available anti-inflammatory medications such as inhaled corticosteroids," she added.

Taranova, who works in the laboratories of Drs. James and Nancy Lee, on the Scottsdale campus of Mayo Clinic, also notes that the findings could be relevant to asthma patients who are diagnosed with other cancers that spread to the lungs. "We suspect that the relationship between lung inflammation and metastasis will not be limited to breast cancer patients," she predicts.

The study was conducted in mice and supported by examination of breast cancer patient records. The results, according to the researchers, offer a biological link: Activation of cells that line blood vessels is required for the movement of pro-inflammatory white blood cells (which occurs in asthma) and for the movement of circulating cancer cells from the blood into lung tissue.

In the study, mice that were exposed to an allergen commonly used in mouse asthma studies and then injected with melanoma cells were compared to control groups of mice that did not suffer from allergic asthma. The allergen-induced pulmonary inflammation in the asthmatic mice was associated with an almost 400 percent increase in lung metastasis in these animals. But in mice treated with a medication currently available to asthma patients that reduces their lung inflammation (corticosteroids self-administered using hand-held inhalers), the rate of metastasis fell to that seen in mice that were not exposed to an allergen.

"Our long-term goal is to continue our retrospective study of breast cancer patients, eventually translating these studies into a multi-center prospective examination of cancer patients," Taranova said. "We want to define the specific aspects of asthma that link lung metastasis and pulmonary disease."

The Drs. Lee advise that many questions need answering, including whether asthmatics who regularly use anti-inflammatory corticosteroids experience a side benefit of reduced risk for lung metastasis and whether people who have allergies - but not asthma - are at the same risk.

Originally, Lee laboratories suspected that asthma patients would have limited lung metastasis. "However, as in most things in science, we have learned much more from studies disproving our flawed hypotheses than from studies confirming our preconceived ideas," Tarnova said.

Mayo Clinic is the first and largest integrated, not-for-profit group practice in the world. As a leading academic medical center in the Southwest, Mayo Clinic focuses on providing specialty and surgical care in more than 65 disciplines at its outpatient facility in north Scottsdale and at Mayo Clinic Hospital. The 208-licensed bed hospital is located at 56th Street and Mayo Boulevard (north of Bell Road) in northeast Phoenix, and provides inpatient care to support the medical and surgical specialties of the clinic, which is located at 134th Street and Shea Boulevard in Scottsdale.

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About Mayo Clinic

Mayo Clinic is the first and largest integrated, not-for-profit group practice in the world. Doctors from every medical specialty work together to care for patients, joined by common systems and a philosophy of "the needs of the patient come first." More than 3,300 physicians, scientists and researchers and 46,000 allied health staff work at Mayo Clinic, which has sites in Rochester, Minn., Jacksonville, Fla., and Scottsdale/Phoenix, Ariz. Collectively, the three locations treat more than half a million people each year. To obtain the latest news releases from Mayo Clinic, go to www.mayoclinic.org/news. For information about research and education visit www.mayo.edu. MayoClinic.com is available as a resource for your health stories.