Patterns of survival among patients with myeloproliferative neoplasms diagnosed in Sweden from 1973 to 2008: a population-based study

Abstract

Purpose: Reported survival in patients with myeloproliferative neoplasms (MPNs) shows great variation. Patients with primary myelofibrosis (PMF) have substantially reduced life expectancy, whereas patients with polycythemia vera (PV) and essential thrombocythemia (ET) have moderately reduced survival in most, but not all, studies. We conducted a large population-based study to establish patterns of survival in more than 9,000 patients with MPNs.

Patients and methods: We identified 9,384 patients with MPNs (from the Swedish Cancer Register) diagnosed from 1973 to 2008 (divided into four calendar periods) with follow-up to 2009. Relative survival ratios (RSRs) and excess mortality rate ratios were computed as measures of survival.

Results: Patient survival was considerably lower in all MPN subtypes compared with expected survival in the general population, reflected in 10-year RSRs of 0.64 (95% CI, 0.62 to 0.67) in patients with PV, 0.68 (95% CI, 0.64 to 0.71) in those with ET, and 0.21 (95% CI, 0.18 to 0.25) in those with PMF. Excess mortality was observed in patients with any MPN subtype during all four calendar periods (P < .001). Survival improved significantly over time (P < .001); however, the improvement was less pronounced after the year 2000 and was confined to patients with PV and ET.

Conclusion: We found patients with any MPN subtype to have significantly reduced life expectancy compared with the general population. The improvement over time is most likely explained by better overall clinical management of patients with MPN. The decreased life expectancy even in the most recent calendar period emphasizes the need for new treatment options for these patients.

Figures

Fig 1.

Cumulative relative survival among patients with myeloproliferative neoplasms (MPNs) in Sweden, stratified by subtype, during the whole study period from 1973 to 2008. ET, essential thrombocythemia; MPN-U, MPN unclassifiable; PMF, primary myelofibrosis; PV, polycythemia vera; RSR, relative survival ratio.

Fig 2.

Cumulative relative survival among patients with myeloproliferative neoplasms (MPNs) in Sweden, stratified by subtype, diagnosed (A) during the years 1993 to 2008 and (B) during the most recent calendar period of 2001 to 2008. ET, essential thrombocythemia; MPN-U, MPN unclassifiable; PMF, primary myelofibrosis; PV, polycythemia vera; RSR, relative survival ratio.

Fig 3.

Cumulative relative survival among patients with myeloproliferative neoplasms in Sweden stratified by calendar period of diagnosis. RSR, relative survival ratio.

Fig 4.

(A) Cumulative relative survival among patients with myeloproliferative neoplasms (MPNs) in Sweden stratified by age at diagnosis and (B) estimates of 5-year cumulative relative survival ratios (RSRs) among patients with MPNs stratified by age and calendar period of diagnosis.