Transplantation's Aftermath: Navigating the Landscape of Post-Hematopoietic Cellular Therapy Neoplasms

Survival post-hematopoietic stem cell transplantation (HCT) is improving, with increasing number of survivors. Second neoplasms following HCTs are of a particular concern.Between Jan2003 and Dec2022, 2650 HCT recipients were retrospectively reviewed, with median follow-up of 108 months (range, 0.13-215). Of those, 1130 (43%) were<18 years old. Allogeneic HCTs were conducted in 1471(56%) patients. Myeloablative conditioning (MAC) was utilized in 2151(81%); and 580(22%) received TBI. At a median of 9 years following transplant, thirty-four patients developed second tumors (1.4%) with a median age at time of HCT of 21 years (range, 0.2-66).Of those: 25 were males (73.5%), 15 received full HLA-matched allogeneic HCTs (83%) two (5.8%) patients had unrelated cord blood HCT (UCB) and one (2.9%) received haplo-HCT, whereas autologous HCTs accounted for 47% (n=16). Underlying diseases were: ALL (n=5; 14.7%), AML (n=4; 11.8%), Hodgkin lymphoma (n=6; 26.2%), non-Hodgkin lymphoma (n=6, 26.2%), multiple myeloma (n=4;11.8%), Fanconi anemia (n=3; 8.8%), CML (n=2; 5.9%), Neuroblastoma (n=1; 2.9%) and Thalassemia (n=1; 2.9%).); cGVHD occurred in 20 (58.8%), and CMV infection/reactivation in 20(58.8%). Stem cell source included peripheral blood in 79.3% (n=27), BM in 14.7% (n=5), and UCB in 2.9% (n=2). Conditioning regimens were MAC (85.3%; n=29) vs RIC in 14.7 % (n=5). TBI-based regimen was utilized in 12 patients (35%). Subsequent hematologic malignancies accounted for 38 % (n=13) of subsequent neoplasms: all were of myeloid origin. While subsequent solid neoplasms occurred in 62% (n=21): mainly squamous cell carcinoma (17.6%; n=6). The 5-year-OS after developing subsequent neoplasms was 82%. No difference in the risk of developing a second tumor was seen between TBI vs non-TBI based conditioning (p=0.075), allogeneic vs autologous TCT(p=0.18), RIC vs MAC(p=0.14), or with or without alkylators (p=0.46)Subsequent neoplasms post-HCTs are known sequelae that adversely impact the OS and the quality of life. In our HCT patient population, the rate of Subsequent neoplasms post is lower than that reported in the literature; however, longer follow-up is needed.