Blood cancers fall into three main categories: leukemia, lymphoma, and myeloma. Each starts in a different part of the blood-forming system and behaves differently, but they all involve the uncontrolled growth of abnormal blood cells that crowd out healthy ones. Within these three groups, there are dozens of distinct subtypes, each with its own outlook and treatment approach.
The Three Main Categories
Leukemia begins in the bone marrow, where blood cells are produced, and typically spills out into the bloodstream. It is the most common blood cancer in the United States and the most common cancer of any kind in children.
Lymphoma starts in white blood cells called lymphocytes, which are part of the immune system. Unlike leukemia, lymphoma cells tend to form solid tumors, most often in the lymph nodes but potentially anywhere lymphatic tissue exists.
Myeloma also originates in the bone marrow, but it specifically affects plasma cells, a type of white blood cell responsible for producing antibodies. When myeloma cells multiply, they can form tumors in multiple bones throughout the body.
Leukemia Types
Leukemia is classified along two axes: how fast it progresses and which cell line it affects. That creates four primary types.
Acute leukemias develop rapidly. The cancerous cells are immature and unable to carry out normal immune functions. Acute myeloid leukemia (AML) is the more common acute form in adults, occurring most frequently in people over 60. Its five-year survival rate is roughly 33%. Acute lymphocytic leukemia (ALL) is more common in children, where treatment advances have pushed the five-year survival rate to about 90% for patients under 20.
Chronic leukemias grow more slowly and involve somewhat more mature cells that can still perform some of their jobs, just not well. Chronic lymphocytic leukemia (CLL) is one of the most common adult leukemias, with approximately 90% of patients diagnosed in 2017 still alive five years later. Chronic myeloid leukemia (CML) has a five-year survival rate around 70% for adults aged 20 and older, a dramatic improvement from decades past thanks to targeted therapies.
The “lymphocytic” types arise from cells that would normally become T cells, B cells, or natural killer cells. The “myeloid” types develop from cells that would become other white blood cells called granulocytes and monocytes.
Lymphoma Types
Lymphoma splits into two broad groups: Hodgkin lymphoma and non-Hodgkin lymphoma. The distinction dates back to 1832, when British physician Thomas Hodgkin first described certain lymph node abnormalities. For a long time, any lymphoma that didn’t match his description was simply called “non-Hodgkin.”
Hodgkin lymphoma is almost exclusively a B cell cancer and has four subtypes. It is one of the most treatable blood cancers. For children and adolescents diagnosed in 2017, the overall five-year survival rate exceeded 98%.
Non-Hodgkin lymphoma (NHL) is a much larger umbrella covering roughly 140 different diseases involving both B cells and T cells. The overall five-year survival rate for NHL is 74%, but that number varies enormously by subtype. The most common aggressive form is diffuse large B cell lymphoma, which itself contains 15 to 20 genetically distinct varieties. The most common slow-growing (indolent) form is follicular lymphoma. Rarer subtypes include mantle cell lymphoma, marginal zone lymphoma, cutaneous T-cell lymphoma, and double-hit lymphoma.
Whether a lymphoma is aggressive or indolent shapes treatment timing. Aggressive lymphomas need prompt treatment but often respond well to it. Indolent lymphomas grow slowly and sometimes require only monitoring at first, though they can be harder to cure completely.
Myeloma and Related Conditions
Multiple myeloma is the primary cancer in this category. Abnormal plasma cells build up in the bone marrow, forming tumors across many bones. As these myeloma cells multiply, they crowd out healthy blood cells, leading to low red blood cell counts, weakened immunity, and reduced clotting ability. They also damage bone directly, which can release excess calcium into the blood and affect the kidneys, nerves, heart, muscles, and digestive system. The five-year survival rate for all stages of multiple myeloma is 64%.
Two related conditions sit on the spectrum before full myeloma develops. Monoclonal gammopathy of undetermined significance (MGUS) involves a small number of abnormal plasma cells (less than 10% of bone marrow) producing an unusual protein detectable in blood or urine, but it is not cancer and often causes no symptoms. Smoldering multiple myeloma is a step closer to active disease, also producing no symptoms, and is usually discovered incidentally through blood work done for another reason. Both conditions are monitored because they can progress to active myeloma over time.
Less Common Blood Cancers
Beyond the big three, two other groups of blood cancers are worth knowing about: myelodysplastic syndromes (MDS) and myeloproliferative neoplasms (MPN).
In MDS, blood stem cells in the bone marrow fail to mature into healthy red blood cells, white blood cells, or platelets. The immature cells don’t work properly and die quickly, either in the marrow or shortly after entering the bloodstream. The result is persistent low blood counts that can cause fatigue, infections, and easy bleeding. MDS can sometimes transform into acute myeloid leukemia.
In myeloproliferative neoplasms, the opposite problem occurs: the bone marrow overproduces one or more types of blood cells. The total number of blood cells rises slowly over time, which can thicken the blood or cause other complications.
Some conditions share features of both groups. Chronic myelomonocytic leukemia (CMML) and atypical chronic myeloid leukemia are the two main examples of these overlap disorders, where the bone marrow both fails to mature cells properly and overproduces them.
How Blood Cancers Are Diagnosed
Diagnosis often starts with a routine complete blood count (CBC) that shows something unusual: too many or too few of a particular cell type, or the presence of immature cells that shouldn’t be circulating in the blood. From there, a bone marrow biopsy is the standard next step, providing a direct look at where blood cells are being made.
A technique called flow cytometry plays a central role in pinpointing the exact type of blood cancer. It uses lasers to analyze the surface markers on individual cells in a blood or bone marrow sample. Healthy cells carry a predictable pattern of surface markers that matches their type and maturity level. Cancer cells show different patterns, and those patterns help distinguish leukemia from lymphoma, identify specific subtypes, and guide treatment decisions. The same technology is used later to track whether treatment is working and to detect any remaining cancer cells.