Merkel cell carcinoma (MCC) is a rare, aggressive neuroendocrine skin cancer with higher incidence among whites, elderly, and immunosuppressed patients. Although immunosuppressed MCC patients are at higher risk of recurrence and MCC-related death, it is unknown whether immunosuppression type is associated with differential outcomes.
We retrospectively evaluated 89 nonmetastatic MCC patients with a diagnosis of chronic immunosuppression. Immunosuppression was categorized as chronic lymphocytic leukemia (31% of cohort), other hematologic malignancies (18%), solid organ transplant (21%), autoimmune disease (21%), and human immunodeficiency virus acquired deficiency syndrome (8%). Progression-free survival (PFS) and MCC-specific survival (MSS) were estimated with the cumulative incidence function. Overall survival (OS) was estimated by the Kaplan-Meier method.
With a median follow-up of 52 months, 53 deaths occurred (42 from MCC, 7 unknown, and 4 non-MCC). Two-year PFS, MSS, and OS were 30%, 55%, and 52%, respectively. Human immunodeficiency virus/acquired deficiency syndrome and solid organ transplant patients were diagnosed with MCC at a younger age (median 55 and 59 y, respectively) and with more advanced stage disease compared with other immunosuppressed subgroups. PFS did not significantly differ among the 5 immunosuppression subgroups (P=0.30), but significant differences were observed in MSS and OS (both P=0.01). Controlling for potential confounders for OS, including age and stage, immunosuppression type was still significantly associated with risk of death (P=0.01).
Among immunosuppressed MCC patients, recurrent MCC is the major cause of mortality. The risk of death from MCC differs among immunosuppression types, suggesting important biological differences in host-tumor immune interactions.
*Division of Dermatology
§Department of Radiation Oncology
∥Division of Medical Oncology, University of Washington
†Clinical Research Division, Fred Hutchinson Cancer Research Center
‡University of Washington School of Medicine, Seattle, WA
Portions of this work were funded from the Cancer Center Support Grant (NCI 5 P30 CA015704-43).
The authors declare no conflicts of interest.
Reprints: Yolanda D. Tseng, MD, Department of Radiation Oncology, University of Washington, 1959 NE Pacific Street, P.O. Box 356043, Seattle, WA 98195. E-mail: firstname.lastname@example.org.