Which Leukemia is Most Common in Adults?

CLL is the Most Common Leukemia in Adults

Chronic lymphocytic leukemia, or CLL, is the most common leukemia in adults in the United States.

What about acute myeloid leukemia, or AML?

  • AML is the most common acute leukemia in adults, which may be another point of confusion. In reference to leukemia, the words acute and chronic have slightly different meanings than they do, say, when talking about acute bronchitis versus chronic bronchitis. Acute leukemia refers to the tendency to progress rapidly, while chronic refers to a leukemia that was historically viewed as a more slow growing malignancy a person might live with for years. Today, chronic leukemias are  known to vary tremendously, with survival times ranging from about 2 to 20 years from the time of diagnosis.


Estimates for 2015

An estimated 54,270 people will be diagnosed with leukemia, according to the American Cancer Society. Here is the breakdown by type:

Acute Myeloid Leukemia:                 20,830

Chronic Lymphocytic Leukemia:     14,620

Chronic Myeloid Leukemia:              6,660

Acute Lymphocytic Leukemia:         6,250

Other Leukemia:                               5,910


CLL Facts and Figures

CLL is considered to be a different manifestation of the same disease as small lymphocytic lymphoma, or SLL -- one of the slow-growing non-Hodgkin's lymphomas. Family history is relevant to CLL; parents, siblings, or children of people diagnosed with CLL have more than twice the risk for developing it themselves.

Most people with CLL feel entirely well, having no symptoms at the time a routine blood count shows high levels of lymphocytes in their circulation, leading to the CLL diagnosis.

Here are some additional facts from the American Cancer Society:

  • About 25 percent of all new cases of leukemia are CLL
  • Average lifetime risk of getting CLL is about 1 in 200
  • Risk of CLL is slightly higher in men than in women
  • Average age at diagnosis is approximately 71 years
  • CLL is rare under the age of 40, and extremely rare in children.

Clues about the Cause

According to the American Cancer Society, researchers believe that CLL begins when B-lymphocytes -- the type of white blood cell that can mature to make antibodies -- continue to divide unchecked and without restraint after encountering and recognizing a foreign antigen. The specifics about how this happens and details of all the steps involved are not yet known, but some of the genetic underpinnings of CLL have been described and are beginning to be better understood.

About 17p Deletion CLL

17p deletion CLL is so named because a piece of a specific chromosome, chromosome 17, is lost -- and, most of the time, along with it goes an important gene called p53 that controls apoptosis, or programmed cell death.

The 17p deletion is found in about 3 to 10 percent of people with CLL, overall. 17p deletion CLL is a form of CLL that is harder to treat; people with 17p deletion CLL tend to be difficult to treat with conventional chemotherapy. The median, or middle value, for life expectancy is less than three years.

For more on this, see the section on 'CLL and 17p deletion' in the linked article.

For more general information on CLL, see the article by Karen Raymaakers.

Background and Sources:

The Leukemia and Lymphoma Society. Facts and Statistics.  Accessed August 2015.

American Cancer Society. Leukemia--Chronic Lymphocytic. Accessed August 2015.

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