Chronic Lymphocytic Leukemia: Basic Facts & Figures

Incidence in Minnesota:

CLL has slightly increased in Minnesota

The CLL incidence rate in Minnesota has slightly increased since 1988, with an annual change of 1.0%. As with national data, incidence rates are about two times higher in males than in females. Minnesota incidence rates are among the highest in the nation in recent years, about 60% higher than the national incidence rate of CLL. Since CLL is often an "accidental finding" of other medical tests, higher rates in Minnesota may be explained in part by good access to medical care. 

Since many CLL patients are never seen in a hospital, the higher than average incidence of CLL in Minnesota may also be explained in part by the fact that the Minnesota Cancer Surveillance System (MCSS) is laboratory-based and has more complete case ascertainment for this cancer than other central cancer registries (which are primarily hospital-based). From 2011 to 2013, an average of 261 cases of CLL in males and 136 cases of CLL in females were diagnosed in Minnesota residents each year.


Incidence in Minnesota by year

Age-adjusted rate of new CLL cases.
Age-adjusted rate of new CLL cases.

The rate of CLL is two times higher among males than females. CLL incidence increased by about 1% per year since 1988. Most recently, the age-adjusted incidence rate of CLL was 8.7 new cases per 100,000 males and 4.3 new cases per 100,000 females.


Incidence in Minnesota by age

Rate of new CLL cases, aggregated from 2004 to 2013.
Rate of new CLL cases, aggregated from 2004 to 2013.

CLL is extremely uncommon among children and young adults; over the last 10 years, less than 10 Minnesotans under the age of 35 were diagnosed with CLL. After that age, rates increase steadily with age for each sex.

What is chronic lymphocytic leukemia (CLL)?

Chronic lymphocytic leukemia (CLL) is one type of leukemia. Leukemia is a cancer of the white blood cells (i.e., leukocytes), and CLL is a cancer of a certain type of white blood cell. Different types of CLL exist, and distinguishing among them is important for treatment decisions and prognoses. Current estimates are that more than 50% of CLL patients are diagnosed "incidentally" from blood work conducted for a different complaint. Symptoms, if present, may include painless swelling of the lymph nodes, fatigue, fever and infection, and/or unexplained weight loss. People can live many years with CLL and have few or no symptoms.

What are the risk factors for CLL?

There are few established risk factors for CLL.

  • Age: The incidence of CLL increases with age and is rare among children (in contrast to the acute types of leukemia).
  • Specific herbicides and insecticides including Agent Orange (used during the Vietnam War), have been linked to an increased risk of CLL, but these pesticides likely account for a small proportion of CLL cases.

How can CLL be prevented?

There are currently no practical strategies for preventing CLL.