Characterization of cancer comorbidity prior to allogeneic hematopoietic cell transplantation

Higher comorbidity by the hematopoietic cell transplantation–comorbidity index increases rates of non-relapse mortality (NRM) and impairs survival following allogeneic hematopoietic transplantation. We explored the effects of cancer as a comorbid condition prior to allogeneic transplantation. Among 356 adult transplant recipients, 54 patients (15%) had 58 comorbid cancers. Among 33 solid cancers (9%), breast (n = 12; 20%) was most common; among 26 comorbid hematologic malignancies (i.e. separate hematologic malignancy not related to primary disease) (7%), lymphoma was most common (n = 14; 24%). In unadjusted analysis, increased risks for NRM were found for cancer comorbidity (HR 2.1, p <.001), solid tumor alone (HR 2.1, p <.001), and hematologic malignancy alone (HR 1.9, p =.03). Cancer comorbidity did not impair 2-year overall survival (HR 1.33, CI 0.92–1.94). Both hematologic and solid cancers likely contribute to elevated risks of nonrelapse mortality, unrelated to recurrence of the cancer comorbidity. Further study is indicated to validate these findings.