Why Does Myelofibrosis Cause My Spleen to Enlarge?

Myelofibrosis is a bone marrow cancer that causes a mutation which disrupts the body’s production of blood cells. Yet, in 90% of myelofibrosis cases, patients end up with splenomegaly (also known more commonly as an enlarged spleen).

How does a bone marrow cancer that affects blood cells cause an enlarged spleen?

Bone marrow stem cells can become either red blood cells, platelets, or white blood cells. Red blood cells bring oxygen to the body’s tissues, platelets help blood to clot, and white blood cells fight off invading germs to prevent infections. The mutation that affects these stem cells and causes myelofibrosis disrupts the body’s production of white blood cells.

This is where the spleen comes in. According to Voices of MPN, the spleen is an organ that helps the immune system by also producing white blood cells, as well as removing damaged blood cells, and storing red blood cells and platelets. To make up for the failing bone marrow, the spleen works overtime to create more white blood cells, remove the damaged ones, and store red blood cells and platelets. As a result of the extra work, the spleen grows larger.

When the spleen grows even slightly larger, it can cause noticeable and painful symptoms. The spleen is located right under the ribs and below the abdomen. As it grows bigger, it will likely cause abdominal, rib, and back pain. It can also cause a false feeling of fullness, often leading to weight loss. Any notice of these signs mean you should immediately consult with a healthcare professional.

Myelofibrosis Treatment Stages

In extreme cases, a doctor may perform a splenectomy to remove the spleen all together, but this comes with several risks including the possibility of stroke. Chemotherapy and radiation therapy are also often used to treat enlarged spleens through killing cancer cells.

The most common first step to reducing spleen size is to use a drug therapy like Ruxolitinib (Jakafi) that targets the mutated cancer cells. This has often proven effective in reducing spleen size and associated symptoms. For patients who have been on Ruxolitinib, and have not seen the hoped-for success, clinical trials are a great option. One clinical trial specifically uses Ruxolitinib, combined with another drug, Parsaclisib, together to increase the success of the drug therapy treatment. You can find more information about this clinical trial, and whether you are eligible to enroll here.