Published online Aug 10, 2016. doi: 10.5306/wjco.v7.i4.324
Peer-review started: February 14, 2016
First decision: March 21, 2016
Revised: April 27, 2016
Accepted: May 17, 2016
Article in press: May 27, 2016
Published online: August 10, 2016
Processing time: 180 Days and 5.5 Hours
AIM: 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).
CONCLUSION: 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.
Core tip: Second primary malignancy (SPM) contributes to worse survival in essential thrombocythemia (ET). We utilized the Surveillance, Epidemiology and End Results database to analyze the risk of SPM in ET patients diagnosed during 2001-2011. Two hundred and one 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 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). An increased risk of SPM, particularly leukemia, may contribute to excess deaths in ET.