Evaluation of the differences between extramedullary and bone marrow relapse in adult acute lymphoblastic leukemia patients in terms of clinical features and survival outcomes.

Abstract

e19516 Background: Acute lymphoblastic leukemia (ALL) in adult patients is an uncommon and difficult-to-treat hematological malignancy that is characterized by excess lymphoblasts in the bone marrow (BM). Although many patients achieve remission with chemotherapy, relapse rates are high and survival outcomes in adults are worse than pediatric patients. With uncontrolled proliferation and accumulation of these lymphoblasts, normal hematopoiesis is suppressed and infiltrates various extramedullary (EM) regions. The aim of this study is to evaluate the difference between EM and BM relapse in adult ALL patients in terms of clinical features and survival outcomes. Methods: In this study, we retrospectively analyzed 108 patients who were diagnosed as ALL and treated in our tertiary care center between 2003 and 2019. Statistical analyses were performed using the SPSS software version 25. Results: The study included 108 patients, consisting of 64 males and 44 females with a median age of 30 (range: 17-79 years). The majority of cases were B-cell in origin; 87 (80.6%) patients had B-ALL and 21 (19.4%) had T-ALL. Median follow-up duration for all patients was 21.1 months (range: 0.49-158.7 months). In the follow-up, 28 patients (25.9%) were received allogeneic hematopoietic stem cell transplantation. A total of 27 (25%) patients relapsed during the follow-up period. In 15 (13.9%) of 27 patients, only BM relapse was observed. EM relapse was observed in 12 (11.1%) patients. EM localizations were identified: brain [n = 2, 1.8%], lung [n = 1, 0.92%], retroperitoneum region [n = 1, 0.92%], kidney [n = 2, 1.8%], breast [n = 1, 0.92%], vertebral column [n = 3, 2.7%], spleen [n = 1, 0.92%], and uvea [n = 1, 0.92%]. All of the patients relapsed with bone marrow were B-ALL. Five of the patients (41.7%) with EM relapse were T-ALL (p = 0.006). No significant difference was observed in terms of gender (p = 0.16) and age (p = 0.12) in patients with BM relapse and EM relapse. Median overall survival (OS) was 42.3 months (95% CI: 15.6-69.0) for patients with BM relapse and 32.8 months (95% CI: 20.0-45.5) for patients with EM relapse (p = 0.42). Conclusions: In conclusion, EM relapse is common in ALL patients. We observed that EM relapse is more frequent, especially in patients with T-ALL cell origin. no significant difference was observed in both groups in terms of OS. ALL patients should be carefully followed up in terms of EM relapses as well as bone marrow relapse.