What is blood cancer?

What is Blood Cancer?

Blood cancer is a group of malignant diseases that originate from cells in the blood, bone marrow, or lymphatic system, characterized by abnormal cell growth that disrupts normal blood cell production and immune function. 1, 2

Major Categories of Blood Cancer

Blood cancers are divided into three primary types, each affecting different components of the hematopoietic system:

Leukemia

• Malignancy that starts in blood-forming tissues, especially the bone marrow, characterized by clonal expansion of abnormal blood cells 1
• Acute myeloid leukemia (AML) is the most common form of acute leukemia in adults and accounts for the largest number of annual deaths from leukemias in the United States 1
• Includes subtypes such as acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), chronic myeloid leukemia (CML), and chronic lymphocytic leukemia 1

Lymphoma

• Cancer affecting the lymphatic system, which is part of the body's immune network 2
• Includes Hodgkin lymphoma and non-Hodgkin lymphoma as major subtypes 1, 3
• Non-Hodgkin lymphoma incidence is rapidly increasing in some regions, particularly in association with HIV infection 3

Multiple Myeloma

• Malignant neoplasm of plasma cells that accumulate in bone marrow, leading to bone destruction and marrow failure 1
• Accounts for approximately 1.8% of all cancers and slightly more than 15% of hematologic malignancies in the United States 1
• Characterized by production of monoclonal immunoglobulin, causing skeletal damage, hypercalcemia, renal insufficiency, anemia, and infections 1

Additional Blood Cancer Categories

Myelodysplastic Syndromes (MDS)

• Borderline conditions that can progress to acute leukemia 2
• Often grouped with myeloproliferative neoplasms in classification systems 1

Myeloproliferative Neoplasms (MPNs)

• Include chronic neutrophilic leukemia, chronic eosinophilic leukemia, and other rare subtypes 1
• Represent a heterogeneous group with varying clinical manifestations and prognoses 1

Key Distinguishing Feature

Blood cancers are classified as "liquid tumors" because the cancer is present in body fluids (blood, lymph, bone marrow) rather than forming solid masses. 4 This fundamental characteristic distinguishes them from solid organ cancers and affects both their behavior and treatment approaches 4.

Clinical Impact

• Blood cancers account for approximately 9.6% of new cancer diagnoses in the United States, with an estimated 184,130 new cases annually 1
• These malignancies represent the fifth most common cancer in some countries, with approximately 38,000 people diagnosed yearly in Britain 2
• The median age at diagnosis varies by type, with AML having a median age of 67-71 years, while multiple myeloma has a median age of 69 years 1

Interconnected Nature

Because blood, bone marrow, and lymph nodes are naturally connected through the immune system, a disease affecting one tissue will often affect the others as well. 2, 5 This interconnection explains why blood cancers frequently present with systemic manifestations rather than localized disease 2.