Blood cancer constitutes a variety of hematologic malignancies involving white blood cells (WBCs), red blood cells (RBCs) and platelets. With advances in genetic and molecular technologies and the ability to characterize various types of immunological markers, our understanding of blood cancers and ability to diagnose and treat them have undergone tremendous progress.
What causes blood cancers?
Most blood cancers involve disruptions of the hematopoietic and immune systems. During the transformation of normal cells into cancerous cells (oncogenic process), both the common myeloid and common lymphoid progenitor populations arising from hematopoietic stem cells (HSCs) undergo uncontrolled proliferation. Based on the population affected, different types of blood cancers have been identified.
The three major types of blood cancers
Leukemia, lymphoma (Hodgkin and non-Hodgkin) and myeloma are the three major categories of blood cancer, but based on their phenotypes, several other subcategories have been identified.
Leukemia
Leukemia arises due to an overproduction of WBCs. Based on the starting cell in the bone marrow, leukemia can be lymphocytic or myeloid. Lymphocytic leukemia arises from lymphocyte progenitors whereas non-lymphocytic or myeloid leukemia arises from progenitors of erythrocytes, granulocytes, monocytes or platelets. Based on lineage, maturation stage and speed of disease progression, leukemia is categorized into two types: acute1 or chronic. The prevalence of the disease varies based on age, stage and the type of leukemia (myeloid vs lymphoid).
Lymphoma
Lymphoma arises due to the malignant transformation of lymphocytes. Most lymphomas originate from B cells with only 10–15% being of T and NK cell origin.3 More than 70 types of lymphomas have been described and are grouped in two main categories: Hodgkin and non-Hodgkin lymphoma.
Hodgkin lymphoma
Hodgkin lymphoma (HL) is mostly of B cell origin. It preferentially develops in young adults between 20 and 34 years old. Hodgkin Reed-Sternberg (HRS) cells are a hallmark of Hodgkin lymphoma. They are giant multinucleated abnormal cells constituting the clonal tumor pool of Hodgkin lymphoma. CD30 is the hallmark of HL and HRS cell surface markers.4, 5
Non-Hodgkin Lymphoma (NHL)
Non-Hodgkin lymphoma (NHL) is the most common form of lymphoma.6 Surface markers such as CD20, CD30 and CD19 are expressed in NHL that are derived from B lymphocytes.7 Flow cytometry–based immunophenotypic analysis of NHL relies on the detection of specific lineage markers of B and T cells.
Myeloma
Myeloma is the result of transformation of plasma cells either due to changes in the bone marrow microenvironment or genetic alterations in plasma cells. Because the tumors develop in multiple locations in the bone marrow and periphery, the disease is also called multiple myeloma.
