This retrospective cohort study utilized comprehensive healthcare data accessed from the National Health Insurance Research Database (NHIRD) of Taiwan. Moreover, 99% of the Taiwanese population were enrolled in the Taiwanese National Health Insurance (NHI), which was a compulsory-enrollment and single-payer social insurance. Researchers were allowed access to each enrolleeā€™s anonymized registration records, including ambulatory care, inpatient data, emergency data, and diagnostic codes for academic purposes using an undisclosed identification code. The diagnostic codes of HSCT and malignancies designated by the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) were identified between 2000 and 2013.