Lymphoma stem cells: A step toward a new therapeutic target.

Since lymphoma is a chemosensitive neoplasm, a complete response can be achieved by systemic chemotherapy, even in the metastatic setting. Even so, relapse occurs in a substantial number of patients with an apparently complete clinical response. It is therefore possible that a subset of lymphoma cells that remain viable during treatment causes the relapse. The cancer stem cell hypothesis postulates the presence of this specific cell population in cancers. It suggests that cancers are derived from cancer stem cells, which are a particular subset of cancer cells with stem-like properties, including self-renewal [1]. Since the existence of cancer stem cells was demonstrated in acute myeloid leukemia [2], various surface markers have been identified to isolate cancer stem cells from such solid cancers as breast, brain, and colon. Although a recent publication suggested the probability of lymphoma stem cells in non-Hodgkin lymphoma [3], it did not offer sufficient data to support the presence of cancer stem cells as an origin of lymphoma. However, given the potential role of cancer stem cells in the pathogenesis of cancers, the possibility of lymphoma stem cells deserves attention, for it could improve our understanding of lymphoma biology and lead to the development of a new therapeutic target for lymphomas.