Paroxysmal Nocturnal Hemoglobinuria and Cancer: High Incidence Of Cancer In a Large Series Of PNH Patients In a Single Center

Since 1964, a total of 56 patients with Paroxysmal Nocturnal Hemoglobinuria clone (PNH) were evaluated in our Hematology Unit. The PNH was evaluated with Ham’s and/or sucrose tests until 1993, when the firsts cytometric analysis of PNH were performed in our Laboratory with CD55 and CD59 markers on granulocytes mainly, and since 2011 also with the FLAER technique. According with PNH Parker´s Classification, most of the patients were Classical PNH type (28 patients), and the remaining included in the other subsets such as 21 PNH in the setting of another bone marrow failure syndrome (BMFS) and 7 PNH subclinical. Most of the patients (70%) displayed an Aplastic Anemia (AA) before or concomitantly with the diagnosis of PNH, and received immunosuppressant drugs (Steroids with/out antithymocyte globulin & Cyclosporine). In four patients an Allogeneic Hematopoietic Transplantation was performed due to a Severe Aplastic Anemia (2 patients), a Classical Severe PNH (before Eculizumab era) or a Myelodysplastic Syndrome. Another patient received a Liver Transplantation because of advanced Hepatitis C related liver failure.

In our PNH series, an unexpected high incidence of cancer has appeared, with 8 patients (14,5%) displaying different hematological or non-hematological cancers in the lasts years:

In our PNH series, cancer reports as one of the most frequent final cause of death, with thrombosis with similar incidence (11 patients of the 56 are dead, with 5 patients dead because thrombosis), although the high incidence and severity of thrombosis episodes in this cohort of patients (20 patients experienced thrombosis with a total of 40 events).

As displayed supra, some of the cancers could be attributed to the therapy applied in particular patients: The two secondary lymphomas after organ transplantation could be explained by the immunosuppression employed in these procedures. Only three patients did not received immunosuppressant drugs before cancer diagnosis. This high mortality cancer rate precludes the indiscriminate use of steroids in PNH patients. This result, never reported before in PNH, merits an investigational survey of cancer incidence in PNH patients in the PNH International Registry.