Dr. Vasyl Vasko of the Uniformed Services University of the Health Sciences said his research suggests that some treatments could be producing more cancer stem cells, which then metastasize as a way to survive the therapy.

"This may help explain why the expression of stem-cell markers has been associated with resistance to chemotherapy and radiation treatments and poor outcome for patients with cancers including prostate, breast and lung cancers," Vasko said Friday in a release.

The research was presented at the American Association for Cancer Research's second International Conference on Molecular Diagnostics in Cancer Therapeutic Development.

The report said the cancer stem-cell markers include Nanog and BMI1, both of which contribute to stem cells' defining ability to renew themselves and differentiate into different cell types. Vasko said these same molecules are found in embryonic stem cells.