Chronic Lymphocytic Leukemia

By Peter Galvin, MD

Chronic lymphocytic leukemia (CLL) is the most common type of leukemia, affects approximately 200,000 people in the U.S., and represents about 1.1% of all new cancers diagnosed in the U.S. The median age at diagnosis is 70 years, with a slight male predisposition. In 2022, it was estimated that about 20,160 people were diagnosed with CLL and about 4,410 people died with it. CLL is a slow growing and slowly progressive disease as its survival rates demonstrate. The 5-year survival rate is 90%, and the 10-year rate is 82%. Most (70 to 80%) patients do not require anti-CLL treatment at the time of diagnosis, and the time to first treatment ranges from months to decades, depending on the clinical and molecular features of the disease.

CLL is characterized by accumulation of immunologically dysfunctional mature B lymphocytes which is why those with CLL have abnormal immune system responses to infections and immunizations, meaning the disease makes them immunocompromised. About 70% of cases are diagnosed incidentally based upon an unexplained lymphocytosis (high white cell count). Most patients have no symptoms at the time of diagnosis. Among those patients with symptoms, about 50% present with symptoms due to lymphadenopathy (enlarged lymph nodes, typically in the groin, neck, or armpits). About 20 to 50% present with symptoms from hepatosplenomegaly (enlarged liver and spleen), and about 5 to 10% present with unintentional weight loss of more than 10% of body weight over 6 months, fever, drenching night sweats, or extreme fatigue. Patients can also present with cytopenia (low cell counts), meaning either anemia (low red cell count), neutropenia (low white cell count), or thrombocytopenia (low platelet count).

Genetic mutations with CLL are common. There are multiple genes/chromosomes that may be involved. These mutations are not inherited, but rather are acquired over the patient’s lifetime, often from environmental exposures to chemicals or radiation. Because these mutations are not hereditable, relatives of patients with CLL do not require testing. Approximately 30 to 50% of those newly diagnosed with CLL have low-risk disease. Of these, only about 8% require treatment in the first 5 years after diagnosis. Therefore, given the median age of CLL diagnosis (70 years), many patients (about 30%) never require treatment. There is no evidence that treating patients with asymptomatic CLL improves survival. Patients with CLL should be advised that they have an increased risk of infection due to their impaired immune system. While live vaccines such as live attenuated influenza vaccine (nasal spray) should be avoided, all patients with CLL should receive recombinant zoster vaccine (for shingles [Shingrix]), COVID-19 vaccines, and inactivated (killed) influenza vaccine on an annual basis.

Observation without treatment is the standard of care. Treatment may be required if the patient develops anemia, thrombocytopenia, neutropenia, or massive progressive or symptomatic lymphadenopathy or hepatosplenomegaly. Treatment is usually comprised of various combinations of chemotherapeutic agents, and remission is common (about 80% of treated patients remain asymptomatic at 5 years after treatment). Finally, about 10% of CLL patients will develop Richter transformation, where CLL is transformed into a high-grade lymphoma (90%) or Hodgkin’s lymphoma (10%), at a rate of 0.5 to 1% per year. Following Richter transformation, survival drops to 3 to 4 months.

For more information go to: www.seer.cancer.gov/statfacts/html/clyl.html

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