Disease Description (Causes and Pathophysiology, Main Symptoms)
Myeloproliferative neoplasms (MPNs) are a group of diseases in which clonal (abnormal) proliferation of hematopoietic stem cells leads to excessive production of red blood cells, white blood cells, and platelets in the bone marrow, or destruction of bone marrow function, resulting in extramedullary hematopoiesis in the spleen and other organs. Major genetic mutations include JAK2 (such as V617F), CALR, and MPL, and activation of these signaling pathways causes abnormal proliferation. Major subtypes include polycythemia vera (PV), chronic myeloid leukemia (CML, BCR-ABL1-positive), essential thrombocythemia (ET), and primary myelofibrosis (PMF).
Main Symptoms
- Increased risk of thrombosis (arterial or venous), peripheral ischemia (pain and coldness)
- Bleeding tendency (when platelet function is abnormal or the platelet count is extremely high)
- Splenomegaly (abdominal discomfort and early satiety)
- Anemia (fatigue and pallor), facial flushing (polycythemia vera)
- Pruritus (especially after bathing), peripheral pain, bruising
In some patients, no symptoms are present, and abnormalities are first detected on blood tests.
Treatment Methods and Precautions
General principles: After risk stratification according to symptoms and the risk of complications (age, previous thrombosis, blood cell counts, etc.), conservative management (observation), symptomatic and preventive treatment (aspirin, transfusion, etc.), cytoreductive therapy (anticancer drugs), targeted therapy (tyrosine kinase or JAK inhibitors), or curative treatment (allogeneic hematopoietic stem cell transplantation) is selected.
Polycythemia Vera (PV)
- First-line: Maintain the target hematocrit (generally, <45% is recommended); perform regular phlebotomy (generally 200–400 mL each time, as needed)
- Thrombosis prevention: Low-dose aspirin (when there are no specific contraindications)
- High risk (age >60, previous thrombosis, etc.): Cytoreductive therapy (hydroxyurea) or interferon (especially for younger patients or those planning pregnancy)
- For symptomatic or refractory disease associated with JAK2 mutations: Consider ruxolitinib and other treatments
Essential Thrombocythemia (ET)
- Low-risk group (asymptomatic, age <60, no history of thrombosis): Observation or low-dose aspirin
- High-risk group (age >60 or a history of previous thrombosis): Hydroxyurea as first-line treatment; anagrelide or interferon as alternatives
- When the platelet count is extremely high, both the risk of bleeding and the risk of thrombosis should be considered
Primary Myelofibrosis (PMF)
- Symptomatic treatment: Transfusions for anemia, erythropoiesis-stimulating agents (ESAs), steroids, androgens, etc.
- Symptoms caused by splenomegaly: Use JAK inhibitors such as ruxolitinib
- Curative treatment: Allogeneic hematopoietic stem cell transplantation (selected according to age, complications, and prognostic factors)
- Observation may be possible when there are no symptoms and the risk of progression to leukemia is low
Chronic Myeloid Leukemia (CML)
- BCR-ABL1-positive: Standard treatment is a TKI (imatinib, dasatinib, nilotinib, etc.)
- Assess the treatment response and decide whether to change treatment according to molecular monitoring (blood BCR-ABL1 levels)
Precautions / Self-Management
- Manage risk factors such as dehydration, prolonged inactivity, smoking, and hormones (especially estrogen) to prevent thrombosis
- Consult the treating physician when using anticoagulants or antiplatelet agents if there is a risk of bleeding
- When planning pregnancy, medication selection (interferon is preferred) and specialist consultation are necessary
- Prevent infections and undergo regular blood tests (blood cell counts, liver and kidney tests, etc.)
Checklist Before an Outpatient Visit (Including Recommended Items to Bring and Sample Questions)
Recommended items to bring
- A list of all medications and supplements currently being taken (including dosage and administration times)
- Copies of recent blood tests (CBC), biochemical tests, and bone marrow and molecular test results (e.g., JAK2/CALR/MPL, BCR-ABL)
- Records of recent transfusions, procedures, and hospitalizations
- A symptom diary (onset, frequency, and type: pain, pruritus, bleeding, symptoms of thrombosis, etc.)
- Records of pregnancy status or pregnancy plans and smoking and alcohol use
Information / Tests to Be Checked at the Outpatient Visit
- CBC (hemoglobin, hematocrit, white blood cells, and platelets), peripheral blood smear findings
- Iron, vitamin B12, and EPO levels (to distinguish polycythemia vera from relative erythrocytosis)
- Bone marrow examination (when necessary), molecular genetic tests (JAK2/CALR/MPL, BCR-ABL)
- Abdominal ultrasound (spleen size), and cardiovascular risk assessment when necessary
Examples of General Questions to Ask the Doctor
- What is the course (prognosis) of this disease, and what are the risk factors?
- What treatment options are currently recommended, and what side effects can be expected?
- What lifestyle changes should be made to prevent thrombosis or bleeding?
- If there are plans for pregnancy or breastfeeding, what treatment adjustments are necessary?
Examples of Disease-Specific Questions
- (Regarding PV) How are the target hematocrit level and frequency of phlebotomy determined?
- (Regarding ET) Should treatment be started based only on the platelet count, or are other factors such as age and history of thrombosis more important?
- (Regarding PMF) What are the indications for allogeneic hematopoietic stem cell transplantation, and what benefits and risks are expected before and after transplantation?
- (Regarding CML) Can treatment be discontinued according to the results of BCR-ABL1 molecular monitoring, and what are the criteria?
Precautions, Complications, and Prevention
Main Complications
- Thrombosis (venous: deep vein thrombosis and pulmonary embolism; arterial: stroke and myocardial infarction)
- Bleeding (platelet dysfunction or acetylation phenomena associated with an extremely high platelet count, etc.)
- Myelofibrosis; anemia, infection, and bleeding due to loss of bone marrow function
- Progression to acute myeloid leukemia (AML): The risk is higher in the order PMF > PV > ET (examples: PMF 10–20%/10 years, PV 2–3%/10 years, ET <1%/10 years)
Prevention and Lifestyle Guidelines
- Actively manage cardiovascular risk factors (hypertension, diabetes, hyperlipidemia, and smoking)
- Drink sufficient fluids and take preventive measures during long flights or bed rest (consider anticoagulation when necessary)
- Inform the treating physician in advance about the blood disorder before trauma-related treatment or surgery
- Regular blood tests and follow-up with the treating specialist are essential
Guidance in Emergencies
- If symptoms suggestive of thrombosis occur, such as sudden severe chest pain, shortness of breath, hemiplegia, or speech impairment, visit the emergency room immediately
- In cases of severe bleeding of unknown cause (vomiting blood, black stools, or a wound that does not stop bleeding), immediately visit a medical institution