Lösemi, or leukemia, is a type of cancer that affects the blood and bone marrow. It occurs when the body produces an excessive number of abnormal white blood cells, which can interfere with the production of normal blood cells. This can lead to symptoms such as fatigue, frequent infections, and easy bruising or bleeding. There are several types of lösemi, including acute and chronic forms, which can affect both children and adults. Treatment options may include chemotherapy, radiation therapy, and stem cell transplants, depending on the specific type and severity of the disease. Early diagnosis and intervention are crucial for improving outcomes.