Splenectomy in Patients with Chronic Myeloid Leukemia or Myeloproliferative Diseases: Outcomes, Complications and Prognostic Implications.
Authors: Tam Constantine S. , Pollock Raphael E. , Manning John , Cortes Jorge , Lin Katherine I. , Thomas Deborah A. , Zhou Lingsha , Kantarjian Hagop , Verstovsek Srdan 
Published: April 2020

Abstract
The results of splenectomy in 110 patients with myeloproliferative disorders (MPD) were analyzed to determine short-term outcome and complications, and long-term impact on AML transformation and survival. Thirty-one patients had CML in chronic(CP; n=10), accelerated(AP, n=10) or blast phase(BP, n=11); 60 myelofibrosis in CP(n=59) or BP(n=1); 8 CMML; and 11 other MPDs. Median characteristics (range): age 58 yrs (16–85), male 60%, time from diagnosis 6 months (0–187), 2 prior therapies (0–7), performance status 1 (0–3), B-symptoms 70%, transfusion-dependent 50%, spleen 15cm (0–30) below LCM. The number of indications for splenectomy was 1 in 44%, 2 in 40%, and ≥3 in 16%, with the most common indications being pain/ local symptoms (54%), anemia/ transfusion dependency (59%) and thrombocytopenia (39%). For patients with anemia/ transfusion-dependency, Hb improved ≥2g/dL &/or transfusion requirement decreased by half in 68% for a median of 13 months. For patients with thrombocytopenia, 66% improved platelet count by &gt;30×10^9/L for a median of 18 months. No patient had deterioration in Hb or Plt post-splenectomy not otherwise explained by disease or concomitant therapy. Complications occurred in 58% patients with the most common being thrombocytosis &gt;1000×10^9/L (17%), venous thrombosis (16%), pneumonia (10%), abdominal collection (9%), leucocytosis &gt;150×10^9/L (6%), painful hepatomegaly (4%) and bleeding (3%). Sites of thrombosis were: 10 portal vein, 3 Budd-Chiari, 3 DVT/PE, 2 splenic vein and 1 SVC obstruction; 2 patients had multiple thrombosis sites. Patients with baseline platelets ≥150×10^9/L were more likely to develop platelets &gt;1000×10^9/L postoperatively (39% v 6%, p&lt;0.001), who in turn were at an increased risk of venous thrombosis (32% v 13%, p=0.05). Median survival was 19 months: most patients died of progressive disease, with only six deaths attributable to surgery, and the occurrence of surgical complications had no impact on survival (p=0.45). In order to assess the impact of splenectomy on AML risk and survival of myelofibrosis patients, we compared outcomes between 53 study patients and 267 control (non-splenectomized) patients from the MD Anderson MPD database. Patient with features of pre-terminal disease (blasts ≥10%, abnormal chromosome 17 or severe cytopenia) were excluded from this analysis. In this comparison, splenectomized myelofibrosis patients experienced inferior survival (median 21 v 46 months, p&lt;0.001), with the difference remaining significant (HR 1.6 p=0.02) after accounting for age, cytogenetics, blast%, monocyte count and Lille score in a multivariate analysis. AML risk was also increased in splenectomized patients, but occurred in only a minority of patients (23% at 4 yrs, v 13% for controls, p=0.01), and splenectomy was not an independent factor for AML development after accounting for peripheral blood blast% (HR 1.3, p=0.008) and Lille score (HR 2.2 p=0.005) in multivariate analysis. The requirement of splenectomy for disease control is an independent predictor of poor outcome in patients with myelofibrosis.