Extramedullary Relapse of Acute Leukemia After Allogeneic Hematopoietic Stem Cell Transplantation —Single Center Experience

To investigate the incidence, risk factors and clinical outcome of extramedullary relapse (EMR) following allogeneic hematopoietic stem cell transplantation (allo- HSCT).

We retrospectively studied the patients with AL (n =410) who underwent allo-HSCT at our center between 2001 and 2012 who developed either bone marrow (BM) or extramedullary (EM) relapse.

1. The incidence of overall relapse was 22% (90/410), with 68 cases of medullary relapse (16.6%), 13 cases of isolated extramedullary relapse (3.2%) and 13 cases of extramedullary relapse with concomitant bone marrow involvement (3.2%); 2. The 3-year overall survival (OS) of EMR and BMR was 14.1% and 13.8% respectively (p=0.027). Not only the 6-month overall survival (OS), but also the 12-month OS, the 24-month OS and the 36-month OS post relapse in patients with EMR was significantly better than that of BMR patients. Acute lymphoblastic leukemia (ALL) subtype (P=0.006) and complete remission status (P=0.047) at transplant yielded better 6-month survival in patients with EMR.; 3.Relapse sites included central nervous system (n=17), testicular (n=4), lymphatic (n=2), skin (n=2), bone (n= 1); 4.CNSL is the most common subtype of EMR. Univariate analysis showed that the factors associated with CNSL included ALL as the underlying diagnosis (relative risk [RR] = 2.727, p= 0.044) and sourse of peripheral blood stem cell (RR= 1.412, P= 0.018).

CNSL is the most common subtype of EMR. Univariate analysis showed that ALL subtype and source of PBSC were associated with an increased risk of CNSL relapse. Patients with EMR have better overall survival compared with those with BMR.

No relevant conflicts of interest to declare.