Myelofibrosis (MF) is a rare form of leukemia, or cancer of the blood. In its early stages, many people have no signs of symptoms, but myelofibrosis is a serious disease that scars the bone marrow, which is where your blood forms, and disrupts the marrow’s ability to make healthy blood cells. The prognosis for someone with MF varies widely – some people have no symptoms for many years, while in others, the disease progresses more quickly. Survival can range anywhere from months to more than a decade, but recently, researchers have made advances in treatment that have improved the outlook for many of those with MF. To understand this variable disease, which primarily strikes older people, here’s a look at how myelofibrosis affects your body over time. How Myelofibrosis Starts Myelofibrosis begins with a mutation in the cells that make blood, often in a gene called JAK2. The abnormal cells produce large numbers of other damaged cells, leaving little room for healthy ones. These non-functional cells replace some of your bone marrow, hardening the spongy material it’s made of and causing scars and inflammation. When your marrow can’t produce healthy cells, your spleen or liver may start to produce blood cells instead. How Myelofibrosis Affects Your Organs Many patients with MF will have symptoms from an enlarged spleen, including pain when you breathe deeply, loss of appetite, and feeling full after eating a small amount of food. Normally, blood flows from the spleen to your liver through a large blood vessel called the portal vein. If your spleen gets bigger and makes too much blood, which is common in myelofibrosis, it can lead to high blood pressure in the portal vein. That, in turn, forces blood into small veins in your esophagus and stomach. These fragile, stretched veins can burst, and you may have gastrointestinal bleeding. When your body is forming blood in your liver and spleen, you may develop tumors elsewhere in your body, such as the lymph nodes, spinal cord and lungs. You may also feel confused because your liver isn’t clearing toxins from your body efficiently, and these toxins affect the brain. Your heart has to work harder to get oxygen to the brain and other organs when you have a low red blood count, so you feel fatigued and you may also have some chest pain or dizziness. How Myelofibrosis Affects Other Areas Of Your Body Over time, you may not only lack healthy red blood cells, but you may also have a low platelet count. Platelets cause clotting, so if you don’t have enough of them, you will bleed and bruise more easily. The scarring in your bone marrow can inflame the tissue around the bone and make your bones and joints ache. You can also have joint pain from gout, caused by too much uric acid, which deposits sharp crystals in your joints. You may also have intense itching, run a low fever, or have night sweats. Other Potential Complications A small number of people with myelofibrosis eventually develop acute myelogenous leukemia, or AML, a type of blood cancer that progresses rapidly and is treated by chemotherapy. Researchers are learning more about how to predict who is at risk for developing AML and how to lower the chance of patients getting it. If you are diagnosed with myelofibrosis, you may not need treatment right away. Your doctor will closely monitor you for signs of progression. When you do need treatment, there are medications your doctor can give you, including one that targets the JAK gene mutation, chemotherapy treatments that destroy the cancer cells, and therapies like blood transfusions. A few people may qualify for a bone marrow transplant, which has the potential to cure myelofibrosis, but it’s a risky procedure and can be fatal. There are also treatments and therapies that address the symptoms of myelofibrosis and alleviate discomfort and fatigue. Myelofibrosis is a disease that can differ from individual to individual, so if you have MF, talk to your healthcare provider to make sure you understand the condition and your treatment options.