What are the long term effects of taking hydroxycarbamide

The short version: the evidence retrieved does not answer the question of long-term effects of hydroxycarbamide in the general population. It mostly studies a different drug or a different disease.

The evidence you provided is a mix of studies on anagrelide (a different drug) [1], a single case report of platelet oscillations [2], a vaccine response study in myelofibrosis patients [3], and a trial in children with sickle cell anemia [4]. None of these are designed to establish the long-term safety profile of hydroxycarbamide in adults with the conditions it is most commonly prescribed for, like polycythemia vera or essential thrombocythemia.

The TWiTCH trial in sickle cell children [4] is the only randomized controlled trial here. It found that over 24 months, hydroxycarbamide was non-inferior to transfusions for preventing strokes, with more serious adverse events in the hydroxyurea arm (23 vs 10) [4]. That is a short-term trade-off in a specific pediatric population, not a long-term safety picture for adults. The anagrelide study [1] reports a 2% rate of acute myeloid leukemia over a median 12.5-year follow-up, but that is for a different drug, not hydroxycarbamide. The case report [2] is a single patient observation, not population evidence.

The evidence retrieved does not contain a single long-term safety study of hydroxycarbamide in adults with myeloproliferative neoplasms. The gap itself matters. The question of cumulative toxicity, leukemogenic risk, or impact on survival over decades is simply not answered by the studies provided.

My call: the evidence retrieved does not address the long-term effects of hydroxycarbamide in the populations where it is most used. Confidence: not clear.