Chronic lymphocytic leukemia (CLL) is a cancer of the blood that involves an increased number of white blood cells existing in the lymphoid tissue.

Over time, the cancerous cells increase, leaving less room for healthy blood cells. There are two types of CLL: indolent CLL, which is slow-growing and can remain stable for years without treatment, and aggressive CLL, which is fast-growing and requires more immediate treatment.

Aggressive CLL is also associated with an onset of symptoms that emerge as the cancerous blood cells leave less room for the healthy blood cells. You may feel tired, have difficulty warding off infections, or show other signs of the disease.

Aggressive CLL is a fast-growing subtype of CLL. CLL is the most common form of leukemia in adults in the Western world. Because it develops rapidly, you will likely need immediate treatment following diagnosis.

According to a 2020 study, doctors may use the immunoglobulin heavy-chain variable region gene (IGHV) mutational status to determine whether someone has aggressive CLL. People with a mutated IGHV have a slower-growing form of CLL, while people with unmutated IGHV have a faster-growing, more aggressive form of the disease.

The study also notes that about 50% of people diagnosed with CLL will need to start treatment within 5 years of diagnosis.

What is the most aggressive form of CLL?

The most aggressive form of CLL occurs when CLL transforms into what is known as Richter’s syndrome. Experts describe the syndrome as occurring when CLL changes to a more aggressive type of lymphoma, most commonly diffuse large B cell lymphoma.

Can CLL become aggressive?

About 3% to 15% of all cases of CLL will transform into Richter’s syndrome. If this transformation occurs, the outlook worsens. Treatments will typically involve chemotherapy and stem cell transplants, when possible.

According to a 2020 study, people with unmutated CLL have a lower 5-year survival rate than those with mutated CLL. The study reports that the 5-year survival rate is 71% for unmutated (aggressive) CLL and 81% for mutated CLL.

The National Cancer Institute estimates that the overall 5-year survival rate for CLL was about 87.9% in the years 2012 to 2018.

However, keep in mind that all survival rates are estimates designed to help give you an idea of the overall severity of cancer. Several factors affect your likelihood of survival, including:

  • overall health
  • age
  • response to treatment
  • aggressiveness of your CLL
  • stage of the cancer

Your care team should be able to provide you with the best idea of your overall outlook and help provide treatment that will best suit your needs.

In nonaggressive or indolent cases, your doctor may recommend delaying treatment. This is particularly true if you don’t show signs or symptoms of the cancer and if you have typical blood cell counts.

However, they will monitor your condition and begin treatment once it becomes necessary.

If you have the more aggressive form of CLL, you may need more aggressive CLL treatment. Instead of watching and waiting, your doctor may recommend one or more of the following options:

  • chemotherapy
  • targeted drug therapy
  • radiation
  • allogeneic stem cell transplantation

They may also recommend that you join a clinical trial. Clinical trials test new treatment options to try to find safer and more effective treatment options.

Aggressive CLL has a higher chance of causing symptoms. You may experience symptoms and complications such as:

  • anemia, which occurs as a result of a decrease in red blood cells
  • shortness of breath, which can occur during regular physical activity
  • enlarged lymph nodes, which you may notice more in your neck
  • unexplained weight loss that may result from a loss of appetite
  • increased risk of infections of the lungs, skin, kidneys, or other areas, which may be due to decreased immunoglobulin and neutrophil counts in your blood
  • fatigue
  • low grade fevers
  • night sweats

Your treatment team will be able to provide you with the best information about your overall condition. They will also be able to provide treatment based on your needs.

When your doctor or healthcare team makes a CLL diagnosis, make sure to ask for clarity if you are unsure about the terms they are using. They should be able to tell you whether they believe you have an aggressive form of CLL and which treatment options they recommend based on the diagnosis.

Also, you can seek a second opinion from another healthcare professional. They may run additional tests or find additional information that may help guide you to successful treatment.

Aggressive CLL is a fast-growing form of CLL that typically requires treatment right away. If you receive a diagnosis of this condition, you will likely need more aggressive treatment.

Aggressive CLL is associated with an overall worse survival rate and outlook than indolent CLL, but proper and timely treatment can help improve both. You should work closely with your care team to determine the best treatment plan for your situation.