title: Risk of second primary malignancies in a population-based study of adult patients with essential thrombocythemia.
abstract: OBJECTIVE
  To determine the risk of second primary malignancy (SPM) and survival of patients with essential thrombocythemia (ET).
  
  
  METHODS
  We identified all patients with ET diagnosed during 2001 to 2011 from the Surveillance, Epidemiology and End Results (SEER) 18 database. Actuarial and relative survival methods were used to calculate the survival statistics. We utilized the SEER 13 database to calculate SPM. We used multiple primary standardized incidence ratio (SIR) session of the SEER*Stat software (version 8.1.5) to calculate SIR and excess risk of SPM for ET patients.
  
  
  RESULTS
  Age standardized five-year cause-specific survival was greater for patients < 50 years vs those ≥ 50 years (99.4% vs 93.5%, P < 0.01). Five-year cause-specific survival was lower for men vs women (70.2% vs 79.7%). A total of 201 patients (2.46%) developed SPM at a median age of 75 years. SPMs occurred at an observed/expected (O/E) ratio of 1.26 (95%CI: 1.09-1.45, P = 0.002) with an absolute excess risk (AER) of 37.44 per 10000 population. A significantly higher risk was noted for leukemia (O/E 3.78; 95%CI: 2.20-6.05, P < 0.001; AER 11.28/10000).
  
  
  CONCLUSIONS
  ET patients have an excellent cause-specific five-year survival but are at an increased risk of SPM, particularly leukemia, which may contribute to excess deaths.
authors: Rajesh Shrestha, Division of Hospital Medicine, Department of Medicine, Rhode Island Hospital, Brown University, Rhode Island, RI 02903, United States.
authors: Rajesh
authors: R
authors: Shrestha
authors: Rajesh Shrestha, Division of Hospital Medicine, Department of Medicine, Rhode Island Hospital, Brown University, Rhode Island, RI 02903, United States.
authors: Smith
authors: S
authors: Giri
authors: Rajesh Shrestha, Division of Hospital Medicine, Department of Medicine, Rhode Island Hospital, Brown University, Rhode Island, RI 02903, United States.
authors: Ranjan
authors: R
authors: Pathak
authors: Rajesh Shrestha, Division of Hospital Medicine, Department of Medicine, Rhode Island Hospital, Brown University, Rhode Island, RI 02903, United States.
authors: Vijaya Raj
authors: VR
authors: Bhatt
keywords: Essential thrombocythemia; Second primary malignancy; Survival