As we now know, at least some cancers are created and sustained by errant stem cells. Cancer itself is an age-related condition, the end result of malfunctions in our complex cellular mechanisms - these malfunctions become ever more likely as we accumulate genetic damage over time. Researchers have been broadening their investigations, as Reuters notes: "Continued research into the biology of adult stem cells will aid in the understanding of how cancers originate and develop and may lead to possible new therapies for treating aggressive, currently incurable brain tumors ... This could help explain why these tumors are so hard to cure. Surgery and radiation therapy my remove the tumor, but the cancer could be replenishing itself from the stem cells."