The efficacy and safety of non-myeloablative and myeloablative preconditioning followed by dual-unit umbilical cord blood transplantation from unrelated donors in adult patients with malignant hematologic diseases eligible for allogeneic hematopoietic stem cell transplantation are evaluated through prospective observation and analysis of actual clinical data collection

Inclusion Criteria:

• Aged 19 and older
• Patients scheduled for umbilical cord blood transplantation as a primary allogeneic hematopoietic stem cell transplantation for the treatment of the following hematologic diseases:

Acute leukemia (myeloid/lymphoid/mixed lineage) / Myelodysplastic syndromes / Chronic leukemia (myeloid/lymphoid/monocytic) and myeloproliferative neoplasms / Malignant lymphomas, multiple myeloma / Other malignant hematologic malignancies / bone marrow failure diseases, including aplastic anemia

- If all contents of the consent form are understood and consented to in writing.

Exclusion Criteria:

• Patients with a history of allogeneic hematopoietic stem cell transplantation or those undergoing transplantation for the treatment of engraftment failure (secondary allogeneic hematopoietic stem cell transplantation is an exclusion criterion; however, patients eligible for registration include those undergoing their first allogeneic stem cell transplantation following an autologous stem cell transplantation).
• Patients with severe, uncontrolled infections or severe cardiopulmonary dysfunction, as judged by the investigator.
• Patients with an ECOG Performance Status (PS) greater than 3 or those receiving mechanical ventilation in the intensive care unit.
• Patients who do not consent to participate in the study or those deemed unsuitable for sincere participation by the attending physician.

Adult patients with malignant hematologic diseases who are eligible for allogeneic hematopoietic stem cell transplantation