Differences attributed to older and younger age. Cumulative incidence of IPS stratified by conditioning regimen among allogeneic HSCT patients aged 40 years or younger (panel A; n = 467) or older than 40 years (panel B; n = 633). Cumulative incidence rates of IPS among younger patients (panel A; aged 40 years or younger) were 3.4%, 9.5%, 5.5%, and 3.2% after more than 12 Gy TBI-based (dotted line; n = 175), 12 Gy TBI-based (semibroken line; n = 116), or non-TBI–based (broken line; n = 145) conventional conditioning, or nonmyeloablative (solid line; n = 31) conditioning, respectively. Cumulative incidence rates of IPS among older patients (panel B; older than 40 years) were 13%, 18%, 5.8%, and 2.0% after more than 12 Gy TBI-based (dotted line; n = 98), 12 Gy TBI-based (semibroken line; n = 140), or non-TBI–based (broken line; n = 243) conventional conditioning, or nonmyeloablative (solid line; n = 152) conditioning, respectively.