Leukemia is a type of cancer that affects the blood-forming tissues of the bone marrow and lymphatic system. Usually, they detrimentally impact the white blood cells that are responsible for protecting the body from infections. It affects both, adults and children, however, it is more common in adults. Likewise, Caucasians and men suffer from an increased risk of leukemia. It is characterized by signs and symptoms such as fever, chills, fatigue, frequent or severe infections, swollen lymph nodes, easy bleeding or bruising, petechiae (tiny red spots on the skin), bone pain, excessive sweating, unexplained weight loss, and recurrent nosebleeds.

Researchers still haven’t been able to narrow down the exact cause of leukemia. However, it is strongly suspected to be linked with a combination of environmental and genetic factors that lead to genetic mutation of cells in the blood or bone marrow. The following are the primary types of leukemia. Some of these might be acute, (i.e., the symptoms develop faster, therefore, they require timely and aggressive treatment). On the other hand, chronic leukemia develops slowly so they don’t produce any symptoms in the early stages:

1. Acute lymphocytic leukemia (ALL)
   The most common type of cancer in children, ALL advances quickly, replacing healthy cells with abnormal cells that don’t mature properly. These leukemia cells spread to different parts of the body, and further keep multiplying at a rapid pace. Since this type of cancer can reach body parts such as the brain, liver, and lymph nodes, it might exhibit multiple symptoms. ALL can also affect adults.
2. Acute myelogenous leukemia (AML)
   AML can affect anyone, though it is commonly observed in adults. Like ALL, AML is also an aggressive form of cancer that develops in the blood and bone marrow. It is considered to be the most common forms of leukemia.
3. Chronic lymphocytic leukemia (CLL)
   A type of cancer that progresses slowly, CLL originates in the lymphocytes found in the bone marrow and then spreads to the blood. After a point, it might also spread to organs such as the liver, lymph nodes, and spleen. CLL occurs when numerous abnormal lymphocytes develop, overwhelming healthy cells, thereby making it challenging for the body to fight infections.
4. Chronic myeloid leukemia (CML)
   Typically seen in adults, CML begins in the cells that produce blood in the bone marrow and eventually makes its way into the blood. In the initial stage, the patient might experience no symptoms, this could be for months or even years, before entering an aggressive stage where the cancer cells begin multiplying rapidly, triggering acute symptoms.
5. Hairy cell leukemia (HCL)
   A rare subtype of CML, hairy cell leukemia (HCL) progresses slowly. It starts when the bone marrow generates an abnormal number of B cells (lymphocytes), a kind of white blood cell that fights diseases. As cancer advances, the body produces lesser healthy red blood cells, platelets, and white blood cells.
   
6. Myelodysplastic syndrome (MDS)
   MDS is a cluster of diseases in which the bone marrow makes inadequate red blood cells, white blood cells or platelets. Doctors often diagnose this condition by examining the changes in the number and shape of blood cells and bone marrow. It is also known as a preleukemic condition because some patients develop acute leukemia as a complication of this disorder.