Study Suggests How Cancers Spread to Lungs

ByABC News
September 29, 2008, 7:56 PM

Sept. 30 -- MONDAY, Sept. 29 (HealthDay News) -- Cancers typically spread -- or metastasize -- to specific, predictable locations. Now researchers have a deeper molecular understanding of why, at least for lung metastases in mice.

The finding might someday lead to drug therapies that curb lung cancer metastasis in humans, experts say.

Dr. Yoshiro Maru of the Tokyo Women's Medical University and colleagues report that primary tumors transmit a series of signals throughout the body to "prepare the soil" in the lungs to accept the "seed" of a metastatic cell from solid tumors located elsewhere.

The key players in this process are signaling proteins, which pass back and forth like text messages between the tumor and the premetastatic lung, and then from the premetastatic lung to the tumor and the bone marrow.

"I think the important part of the paper is that it's putting molecules on these pathways between different cells ... and between the primary tumor and the soil," said Mikala Egeblad, an assistant research anatomist at the University of California, San Francisco.

Just as important, the new study suggests that blocking these signaling interactions could inhibit the ability of tumors to metastasize to the lungs.

The findings were published online Sept. 28 in the journal Nature Cell Biology.

According to Dr. Len Lichtenfeld, deputy chief medical officer of the American Cancer Society, much has been learned about what differentiates a benign growth from a more aggressive cancer, as well as the characteristics of cells that break off from a primary tumor and make their way to distant sites within the body -- that is, to metastasize. This study, however, examines how a tumor is able to colonize a particular tissue -- in this case, the lungs.

"This research takes a look at what allows the cancer cells to set up a home in the lungs of the mice," Lichtenfeld said. "By understanding that mechanism, they potentially could incorporate that theory into the treatment of patients and perhaps, by understanding those mechanisms, you may be able to take advantage of that to prevent that [metastasis] from happening."