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.
Keywords: Cancer; comorbidity; hematopoietic cell transplantation; nonrelapse mortality.