Koh et al. Journal of Experimental & Clinical Cancer Research 2011, 30:36 http://www.jeccr.com/content/30/1/36 R E S E A R C H Open Access Factors that contribute to long-term survival in patients with leukemia not in remission at allogeneic hematopoietic cell transplantation Hideo Koh1, Hirohisa Nakamae1*, Kiyoyuki Hagihara1, Takahiko Nakane1, Masahiro Manabe1, Yoshiki Hayashi1, Mitsutaka Nishimoto1, Yukari Umemoto1, Mika Nakamae1, Asao Hirose1, Eri Inoue1, Atsushi Inoue1, Masahiro Yoshida1, Masato Bingo1, Hiroshi Okamura1, Ran Aimoto1, Mizuki Aimoto1, Yoshiki Terada1, Ki-Ryang Koh1, Takahisa Yamane1, Masahiko Ohsawa2 and Masayuki Hino1 Abstract Background: There has been insufficient examination of the factors affecting long-term survival of more than 5 years in patients with leukemia that is not in remission at transplantation. Method: We retrospectively analyzed leukemia not in remission at allogeneic hematopoietic cell transplantation (allo-HCT) performed at our institution between January 1999 and July 2009. Forty-two patients with a median age of 39 years received intensified conditioning (n = 9), standard (n = 12) or reduced-intensity conditioning (n = 21) for allo-HCT. Fourteen patients received individual chemotherapy for cytoreduction during the three weeks prior to reduced-intensity conditioning. Diagnoses comprised acute leukemia (n = 29), chronic myeloid leukemia-accelerated phase (n = 2), myelodysplastic syndrome/acute myeloid leukemia (MDS/AML) (n = 10) and plasma cell leukemia (n = 1). In those with acute leukemia, cytogenetic abnormalities were intermediate (44%) or poor (56%). The median number of blast cells in bone marrow (BM) was 26.0% (range; 0.2-100) before the start of chemotherapy for allo-HCT. Six patients had leukemic involvement of the central nervous system. Stem cell sources were related BM (7%), related peripheral blood (31%), unrelated BM (48%) and unrelated cord blood (CB) (14%). Results: Engraftment was achieved in 33 (79%) of 42 patients. Median time to engraftment was 17 days (range: 9-32). At five years, the cumulative probabilities of acute graft-versus-host disease (GVHD) and chronic GVHD were 63% and 37%, respectively. With a median follow-up of 85 months for surviving patients, the five-year Kaplan-Meier estimates of leukemia-free survival rate and overall survival (OS) were 17% and 19%, respectively. At five years, the cumulative probability of non-relapse mortality was 38%. In the univariable analyses of the influence of pre-transplant variables on OS, poor-risk cytogenetics, number of BM blasts (>26%), MDS overt AML and CB as stem cell source were significantly associated with worse prognosis (p = .03, p = .01, p = .02 and p < .001, respectively). In addition, based on a landmark analysis at 6 months post-transplant, the five-year Kaplan-Meier estimates of OS in patients with and without prior history of chronic GVHD were 64% and 17% (p = .022), respectively. Conclusion: Graft-versus-leukemia effects possibly mediated by chronic GVHD may have played a crucial role in long-term survival in, or cure of active leukemia. * Correspondence: hirohisa@msic.med.osaka-cu.ac.jp 1Hematology, Graduate School of Medicine, Osaka City University, Osaka, Japan Full list of author information is available at the end of the article © 2011 Koh et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.