Medical Oncology and Hematology

Leukemia is a type of cancer that affects the body's blood-forming tissues, including the bone marrow and lymphatic system. It typically involves the white blood cells, which are crucial for fighting infections. In leukemia, the bone marrow produces an excessive number of abnormal white blood cells that do not function properly.¹

Hodgkin lymphoma, formerly known as Hodgkin disease, is a type of blood cancer that develops in the lymphatic system and affects white blood cells called lymphocytes. It occurs when genetic mutations arise in B lymphocytes (B cells), causing them to grow abnormally. Hodgkin lymphoma typically begins in lymph nodes in the neck or chest, but it can also develop in nodes under the arms, in the groin, abdomen, or pelvis. It is one of the two main types of lymphoma, the other being non-Hodgkin lymphoma.³

Non-Hodgkin lymphoma (NHL) is a type of cancer that begins in white blood cells called lymphocytes, which are part of the immune system. It refers to a group of related lymphomas that share certain characteristics. Unlike Hodgkin lymphoma, which is a distinct form with different treatment approaches, NHL most often affects adults but can also occur in children. It usually starts in the lymph nodes or other lymph tissue, though it can sometimes involve the skin.²

Multiple myeloma is a cancer of the plasma cells, a type of white blood cell found in the bone marrow. It is relatively uncommon in the U.S. and often grows slowly, with few or no symptoms in its early stages, making early diagnosis difficult. Symptoms may not appear until the disease has progressed.

Myelodysplastic syndromes (MDS), also known as myelodysplastic neoplasms, are conditions that can occur when the blood-forming cells in the bone marrow become abnormal, resulting in the marrow not making enough healthy new blood cells. This leads to low levels of one or more types of blood cells. MDS is considered a type of cancer.⁴

Myeloproliferative neoplasms (MPNs) are types of blood cancer that begin with an abnormal mutation (change) in a stem cell in the bone marrow. The change leads to an overproduction of any combination of white cells, red cells, and platelets.⁵

There are 3 types:

• Essential thrombocythemia (ET)
• Myelofibrosis (MF)
• Polycythemia Vera (PV)

Anemia is the most common blood disorder, affecting over 3 million Americans. It occurs when the body has too few red blood cells or when those cells don’t function properly. Red blood cells contain hemoglobin, an iron-rich protein that carries oxygen from the lungs to the rest of the body. Anemia is typically diagnosed through a blood test showing low hemoglobin levels—below 13.5 gm/dl in men and 12.0 gm/dl in women, with normal values for children varying by age.⁶

Thrombocytopenia is a condition characterized by a low blood platelet count. Platelets, or thrombocytes, are colorless blood cells that help stop bleeding by clumping together to form clots at sites of blood vessel injury. Thrombocytopenia can result from conditions or medications that affect platelet production, circulation, or destruction, and it can occur in both children and adults.⁷

Sickle cell disease, or sickle cell anemia, is an inherited disorder that affects hemoglobin, the protein in red blood cells that carries oxygen. In this condition, red blood cells become misshaped, often taking on a crescent or "sickle" shape due to a genetic mutation. These sickle-shaped cells are stiff and can block blood flow, leading to reduced oxygen delivery throughout the body.¹²

Thalassemia is an inherited blood disorder that affects hemoglobin production, which is essential for oxygen transport in red blood cells. There are two main types: alpha and beta thalassemia. Severity can range from mild to serious, depending on how much hemoglobin the body produces. Inadequate hemoglobin production can lead to anemia, characterized by fewer healthy red blood cells.¹³

Neutropenia, or low white blood cell count, is a condition that weakens the immune system and may also be referred to as leukopenia, low WBC, or being immunocompromised. It can result from cancer, cancer treatments like chemotherapy or stem cell transplants, or non-cancer-related causes. Common causes include bone marrow cancers (such as leukemia, lymphoma, and multiple myeloma), infections (like COVID-19, EBV, HIV, and hepatitis), immune disorders (such as rheumatoid arthritis and lupus), nutritional deficiencies (like low vitamin B12, copper, or folate), and bone marrow disorders like myelodysplastic syndromes. In some cases, the cause remains unknown, as in chronic idiopathic neutropenia (CIN).⁸

Hemophilia is a rare genetic disorder in which the blood doesn’t clot properly due to a lack of clotting factors. While small cuts usually aren’t serious, people with severe hemophilia are at risk for internal bleeding, especially in joints like the knees, ankles, and elbows, which can lead to serious tissue or organ damage.⁹

Deep vein thrombosis (DVT) is a condition where a blood clot forms in a deep vein, typically in the legs. It can cause pain or swelling, though some people have no symptoms. DVT can occur due to medical conditions affecting blood clotting or from prolonged immobility, such as during long travel, bed rest, or recovery from surgery or illness.¹⁰

A pulmonary embolism (PE) is a serious condition where a blood clot blocks a blood vessel in the lungs, often after traveling from another part of the body, like the leg or arm. This blockage restricts blood flow, reduces oxygen levels, and raises pressure in the lung’s arteries. PE is a medical emergency that requires immediate diagnosis and treatment.¹¹