Addition of Hydroxycarbamide to Aspirin in Essential Thrombocythemia Without High-Risk Features

Key Points

  • The addition of hydroxycarbamide to aspirin did not improve outcomes.
  • The overall rate of the vascular composite primary endpoint was 0.93 per 100 patient-years.

In a long-term follow-up of a study reported in the Journal of Clinical Oncology, Godfrey et al found that the addition of cytoreductive therapy with hydroxycarbamide to aspirin did not improve outcomes in patients with essential thrombocythemia aged 40 to 59 years without high-risk features or extreme thrombocytosis. 

Study Details

In the open-label trial, 358 eligible patients aged 40 to 59 years from 140 sites in the UK, Ireland, Australia, France, and New Zealand were randomized between July 1997 and July 2012 to receive hydroxycarbamide (0.5–2 g once daily adjusted to maintain platelet count at 200–400 x 109/L) plus aspirin (75 mg once daily, 100 mg once daily in Australia; n = 182) or aspirin alone (n = 176). Patients had to have no history of ischemia, thrombosis, embolism, hemorrhage, extreme thrombocytosis (platelet count ≥ 1,500 x 109/L), hypertension, or diabetes requiring therapy.

The composite primary endpoint was time to arterial or venous thrombosis, serious hemorrhage, or death from vascular causes.

Treatment Outcomes

The median follow-up was 73 months, and the total follow-up was 2,373 patient-years.

There was no significant difference between the hydroxycarbamide vs aspirin-alone groups in the composite primary endpoint (11 events in each group; odds ratio [OR] = 0.98, P = 1.0). The incidence of primary endpoint vascular events during follow-up was 0.93 per 100 patient-years. Death occurred in 10 patients in the hydroxycarbamide group vs 7 in the aspirin-alone group (OR = 1.4, P = .5). No significant difference was observed in the incidence of the composite secondary outcome measure of transformation to myelofibrosis, acute myeloid leukemia, or myelodysplasia (OR = 0.79, P = .7).

Adverse Events

No significant differences between groups were observed for the incidence of specific adverse events or when grouped by system. No significant differences were observed in European Organisation for Research and Treatment of Cancer Quality-of-Life Questionnaire C30 summary scores for any study year.

The investigators concluded, “In patients with [essential thrombocythemia) age 40 to 59 years and lacking high-risk factors for thrombosis or extreme thrombocytosis, preemptive addition of hydroxycarbamide to aspirin did not reduce vascular events, myelofibrotic transformation, or leukemic transformation. Patients age 40 to 59 years without other clinical indications for treatment (such as previous thrombosis or hemorrhage) who have a platelet count < 1,500 x 109/L should not receive cytoreductive therapy.”

The study was supported by the Medical Research Council-UK, Cancer Research UK, the French National Cancer Institute, Bloodwise, Wellcome Trust, Kay Kendall Leukaemia Fund, and Leukemia and Lymphoma Society of America.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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