The WHO has designated ET with Jak2 is a chronic cancer. And HU is considered chemo, I notice my platelets rising over 3 years of wellness exams, and asked my primary, he sent me to hematologist, had many blood tests plus bone marrow biopsy to confirm diagnosis. Had second opinion with all lab results, including slides from BMB and concurred with diagnosis. I've been on HU for 3 years now with baby aspirin, rather take meds than have stroke or heart attack.