Cumulative incidence and time to event for leukemic transformation of polycythemia vera

Cumulative incidence and time to event for leukemic transformation of polycythemia vera among 1545 patients stratified by the first cytoreductive drugs they were exposed to. "Leukemogenic" drugs include chlorambucil, P32, and other alkylating agents; "non-leukemogenic," for the purposes of this figure, signifies the use of interferon alfa or anagrelide only; "nothing" refers to patients who were not exposed to any cytoreductive agent.