Blood cancer is an umbrella term for cancers that affect your blood cells and bone marrow. More than 100 types of blood cancer have been discovered, and are divided into three primary categories:

  • Lymphomas: cancers of the lymphatic system, which includes your lymph nodes, spleen, bone marrow, and thymus
  • Leukemias: cancers that develop in your bone marrow or other blood-forming cells and causes abnormal white blood cell production
  • Myelomas: cancers that develop in a type of white blood cell called plasma cells

Each category of blood cancer can be divided into subcategories depending on how the cancer develops and the type of cells affected.

Chronic lymphocytic leukemia (CLL) is the most common form of leukemia diagnosed in adults. Multiple myeloma is the most common form of plasma cell tumor.

In this article, we’ll examine the similarities, differences, and possible connections between CLL and multiple myeloma.

CLL is the most common type of leukemia in adults in Western countries. The American Cancer Society (ACS) estimates that 21,250 Americans will be diagnosed with CLL in 2021.

The name “chronic lymphocytic leukemia” describes how and where it develops. Chronic leukemias tend to develop slowly. Lymphocytic leukemias develop in a type of white blood cell called lymphocytes.

CLL develops in a specific type of lymphocyte in your bone marrow called B cells. Healthy B cells help your body fight infections, but leukemic B cells develop abnormally and can’t fight infections in the same way.

As CLL progresses, your body makes more leukemic B cells that crowd out healthy blood cells. Having fewer healthy white blood cells weakens your immune system and makes you more prone to infections.

People with CLL often don’t have symptoms in the early stages. In fact, about 50 to 75 percent of people with CLL don’t have any symptoms at the time of diagnosis.

The exact cause of CLL is not known, but a number of risk factors have been identified:

  • Family history. People with a parent, sibling, or child with CLL have a 5 to 7 times greater chance of developing it themselves.
  • Age. The average age of CLL diagnosis is 70 years old and it’s rarely found in those younger than age 40.
  • Sex assigned at birth. CLL develops slightly more often in men than women.
  • Race and ethnicity. CLL is most common in people living in North America or Europe and less common in Asia.
  • Agent Orange exposure. Exposure to a chemical used during the Vietnam War called Agent Orange is associated with higher rates of CLL.
  • Monoclonal B-cell lymphocytosis. Monoclonal B-cell lymphocytosis is a condition that causes an elevated level of lymphocytes and can turn into CLL, although the risk is small.

Multiple myeloma is a type of blood cancer that develops in plasma cells. Plasma cells are white blood cells that develop from B cells in response to an infection. They play an important role in your immune system due to their ability to produce antibodies, which are proteins that help your immune system recognize foreign invaders.

In people with multiple myeloma, abnormal plasma cells replicate abnormally and crowd out healthy blood cells.

The ACS estimates that 34,920 Americans will be diagnosed with multiple myeloma in 2021.

It isn’t known exactly why multiple myeloma develops, but it’s thought to start when an abnormal plasma cell replicates more rapidly than it should.

Risk factors for developing multiple myeloma include:

  • Age. Age is the most important risk factor. Multiple myeloma rarely develops in people under 45 years old.
  • Sex assigned at birth. Men are more likely to develop multiple myeloma than women.
  • Race and ethnicity. Myeloma develops at a much higher rate in Black people than those of other groups.
  • Radiation. Exposure to X-rays and other forms of ionizing radiation may increase your chances of developing multiple myeloma.
  • Weight. People who are overweight or have obesity are at a higher risk of developing myeloma.
  • Family history. In some cases, multiple myeloma runs in families. However, most people with multiple myeloma have no relatives with the disease.

CLL and multiple myeloma develop in your bone marrow. Both conditions cause a buildup of abnormal B cells that crowd out healthy blood cells. Due to the similar development, CLL and multiple myeloma cause similar symptoms, and people with either disease often don’t have symptoms in the early stages.

Here’s are some of the similarities between CLL and multiple myeloma:

Symptomsfever, fatigue, frequent infections, unexplained weight loss, loss of appetite, bone pain, swollen lymph nodes, unusual bruising or bleeding
Agemost common in older adults
Sex assigned at birthmore common in men
Typical treatmentstargeted therapy, chemotherapy, radiation therapy, stem cell transplants

CLL develops in B cells in your bone marrow. Multiple myeloma develops in plasma cells, which are B cells that become activated in response to an infection. Cancerous plasma cells produce a type of protein called M protein.

M protein buildup in people with multiple myeloma tends to cause “CRAB” symptoms:

  • C: increased calcium levels
  • R: reduced kidney function
  • A: anemia
  • B: bone problems

Although both conditions cause many of the same symptoms, high levels of calcium and M proteins in multiple myeloma can cause unique symptoms such as vision problems, kidney failure, and confusion.

Here is an overview of the main differences between CLL and multiple myeloma:

CLLMultiple myeloma
Symptomsfever, chills, night sweatsextreme thirst, nausea, vomiting, upset stomach, confusion, constipation, urinary problems, vision loss or problems, kidney failure
Geneticsrisk of developing CLL is 6 times higher if you have a parent with CLLrisk of developing multiple myeloma is twice as high if you have a parent with multiple myeloma
5-year relative survival rateabout 87.2 percentabout 60 percent

It’s still not entirely clear why CLL and multiple myeloma develop, but genetic factors are thought to contribute.

A 2018 study found evidence of a shared genetic correlation between multiple myeloma and CLL. The researchers found 10 gene locations that increase your risk of developing both diseases.

Although CLL and multiple myeloma share many features, it’s rare to have both diseases at the same time. Of 10,725 patients with multiple myeloma treated at the Mayo Clinic from 2000 to 2015, only 28 people also had CLL or small lymphocytic leukemia, which is often considered the same disease as CLL.

CLL and multiple myeloma share some common risk factors such as advanced age and male sex.

CLL and multiple myeloma are two types of blood cancer. CLL causes your body to produce too many abnormal B cells that crowd out healthy blood cells. Multiple myeloma develops in plasma cells, which are a type of B cell that produce antibodies.

The survival rate for multiple myeloma and CLL are relatively high compared to other types of cancer when properly diagnosed and treated. Talk with a healthcare professional if you have any potential warning signs of CLL or multiple myeloma to give you the best chance of having a positive outcome.