Blood and lymphatic cancers（Leukemia）
What is leukemia?
Leukemia is a type of blood cancer that occurs in bone marrow (the tissue in bones that produces blood cells) and lymphoid tissue. Leukemia is usually caused by abnormal proliferation and maturation failure of white blood cells (immune cells), which interferes with normal blood cell production and results in an increase in abnormal white blood cells (depending on the type of white blood cell). This causes abnormal white blood cells to take the place of normal blood cells in the bone marrow and blood, preventing healthy cells from functioning.
Leukemia is generally divided into Acute Leukemia and Chronic Leukemia.
・Acute lymphoblastic leukemia (ALL):
is a disease in which lymphoblasts (a type of white blood cell) proliferate abnormally in the bone marrow and blood. It is usually seen in children and young adults.
・Acute myelogenous leukemia (AML):
a disease in which abnormal bone marrow cells (hematopoietic stem cells) grow abnormally in the bone marrow and can occur in people of all ages.
・Acute promyelocytic leukemia (APL)）：
is a disease of abnormal proliferation of promyelocytes (a type of white blood cell promyelocytes in the bone marrow). It is associated with certain genetic abnormalities. The main symptoms of acute leukemia include anemia, increased white blood cell counts, bleeding tendency, swollen lymph nodes, fever, bone pain, and abdominal swelling due to swelling of the spleen and liver.
・Chronic lymphocytic leukemia (CLL):
a disease characterized by an abnormal proliferation of mature lymphocytes (B-cell lymphocytes), seen primarily in middle-aged and older adults.
・Chronic myelogenous leukemia (CML):
an abnormal proliferation of myeloid cells (especially myeloid leukocytes) in the bone marrow, usually in middle-aged adults. The main symptoms of chronic leukemia, although not as acute as acute leukemia, include fatigue due to anemia, swollen lymph nodes, infections caused by a weakened immune system, abnormal white blood cell counts, and swelling of the liver and spleen. Chronic leukemia is characterized by a milder progression than acute leukemia.
An example of a proposed treatment for leukemia
Acute leukemia progresses rapidly and requires urgent treatment, while chronic leukemia usually requires long-term treatment.
Treatment of acute leukemia
The primary approach to treat acute leukemia is chemotherapy using high-dose anticancer drugs. This eliminates abnormal white blood cells from the bone marrow and allows normal blood cells to regenerate. Chemotherapy is usually administered with a combination of several anticancer drugs.
Radiation therapy may be used in certain cases. It is usually given for localized disease, and radiation therapy to the bone marrow is rare.
・Hematopoietic Stem Cell Transplantation:
Hematopoietic stem cell transplantation may be considered for some patients with acute leukemia who are at high risk or who have relapsed. This involves replacing the patient’s bone marrow with normal hematopoietic stem cells.
Treatment of Chronic Leukemia
Certain molecularly targeted drugs are used to treat chronic leukemia. These drugs are intended to act specifically on cancer cells and not on normal cells. For example, tyrosine kinase inhibitors (such as Imatinib) are used to treat chronic myeloid leukemia (CML)
Immunotherapy is used to activate a patient’s immune system and facilitate an attack against cancer cells. This includes antibody and CAR-T cell therapies.
For some patients with chronic leukemia, chemotherapy may be an appropriate treatment option. However, higher doses of chemotherapy are not as common as in acute leukemia.