Late Mortality and Causes of Death among Long-Term Survivors after Allogeneic Stem Cell Transplantation

• Allogeneic hematopoietic cell transplantation survivors are at a higher risk of death than the general population
• Chronic graft-versus-host disease by 2 years is a strong risk factor for late mortality
• Risk of mortality due to respiratory/renal cause is high 2 decades after allogeneic hematopoietic cell transplantation
• Risk of mortality due to new nonhematological cancer is high among hematopoietic cell transplantation survivors

We sought to assess the late mortality risks and causes of death among long-term survivors of allogeneic hematopoietic stem cell transplantation (HCT). The cases of 11,047 relapse-free survivors of a first HCT at least 2 years after HCT were analyzed. Standardized mortality ratios (SMR) were calculated and specific causes of death were compared with those of the Japanese population. Among relapse-free survivors at 2 years, overall survival percentages at 10 and 15 years were 87% and 83%, respectively. The overall risk of mortality was significantly higher compared with that of the general population. The risk of mortality was significantly higher from infection (SMR = 57.0), new hematologic malignancies (SMR = 2.2), other new malignancies (SMR = 3.0), respiratory causes (SMR = 109.3), gastrointestinal causes (SMR = 3.8), liver dysfunction (SMR = 6.1), genitourinary dysfunction (SMR = 17.6), and external or accidental causes (SMR = 2.3). The overall annual mortality rate showed a steep decrease from 2 to 5 years after HCT; however, the decrease rate slowed after 10 years but was still higher than that of the general population at 20 years after HCT. SMRs in the earlier period of 2 to 4 years after HCT and 5 years or longer after HCT were 16.1 and 7.4, respectively. Long-term survivors after allogeneic HCT are at higher risk of mortality from various causes other than the underlying disease that led to HCT. Screening and preventive measures should be given a central role in reducing the morbidity and mortality of HCT recipients on long-term follow-up.