April 7 (HealthDay News) -- A single cancer cell can lead to multiple, anatomically distinct lung tumors, U.S. researchers say.
These types of tumors usually look similar, but, until now, it hasn't been clear whether they arise from a single source or are independent, primary tumors, according to background information in the study by a team at the Indiana University School of Medicine in Indianapolis.
The team analyzed 70 lung cancer tumors from 23 female and 7 male patients and concluded that the multiple tumors in 23 (77 percent) of the patients arose from a single cancer cell type.
"Our findings support the current classification of multifocal lung cancers as advanced-stage cancers ... rather than separate primary cancers and the use of therapeutic strategies tailored for patients with advanced-staged cancers," the researchers said in a news release from the Journal of the National Cancer Institute, which published the results online April 7.
The findings "pose both important biological and clinical management questions," two experts wrote in an accompanying editorial in the journal. As many as 8 percent of lung cancer patients have multiple anatomically distinct tumors at the time of diagnosis, noted Adi F. Gazdar and John D. Minna, of the University of Texas Southwestern Medical Center at Dallas.
"Clearly, multifocal lung cancers (without distant metastases) constitute a unique set of tumors having heterogeneous origins and better than expected prognosis and should be classified and treated appropriately," they wrote.
An updated lung cancer classification system is expected sometime in 2009, according to the study.
SOURCE: Journal of the National Cancer Institute, news release, April 7, 2009