I have been asked to explain CLL (Chronic Lymphocytic Leukemia) in easily understood language. I’ll try, though I make no promises, and the attempt may result in less than totally accurate descriptions. The end result, hopefully, will help you understand what is happening in a CLL patient, how the disease will be or is being treated, and a general description of the treatment methods.
CLL is a cancer of the white blood cells. If we define each part of the name, we may be able to understand it a little better. “Chronic” means the disease is on-going. It comes; it is sent into remission; it returns. The cycle is repeated a number of times until the disease no longer responds to treatment.
“Lymphocytic” indicates that the disease involves the lymphocytes. Lymphocytes are a part of the white blood cell system. There are two main components to the white blood cell system: lymphocytes and neutrophils. I like to think of these two as parts of an army. The way I understand it, neutrophils are like the Marines. They are the first on site when an infection is detected. The neutrophils surround the invading cells and destroys them. If they cannot overpower the enemy by themselves, they, like the Marines, call in reinforcements, lymphocytes. Lymphocytes are like cruise missiles, which are programed to seek and destroy specific intruders. Each lymphocyte has characteristics that cause it to attach to specific disease cells. New generation lymphocytes can be programed to fight unknown-to-date diseases. That’s what happens when we are “immunized”. A non-active form of a disease is inserted into the body causing lymphocytes to seek and destroy the new invader. Those and new generation cells retain that knowledge and are able to rapidly destroy any invaders.
“Leukemia” simply indicates the disease involves the blood. This means the cancer is not “localized” as is, for example, lung cancer or breast cancer. CLL is most often detected in a routine blood test, as in my case. On December 6th, 2006, I visited my physician for my annual physical. At the end of the exam, I pointed to a swollen spot on my neck thinking it was nothing to be concerned about. She looked at it and immediately thought I should go to an endocrinologist. Then the blood results were brought to her. The white count was extremely high. Her recommendation changed to an oncologist. Her preliminary diagnosis, CLL. She was right. I have now fought the disease for seven years.
CLL is not usually aggressive. Often, no immediate action is taken, but the patient is carefully observed for up to several years before treatment is indicated. Once treatment is needed, chemotherapy is initiated. The first line of defense is a type of drug known as Purine Analogs. I view these drugs as creating an unfavorable environment. I suppose it could be similar to a localized use of a WMD, weapon of mass destruction. The idea is to make the body unfavorable to the life cycle of the defective lymphocytes. Unfortunately, there is undesirable collateral damage. The bone marrow, where blood cells are created, is damaged as well causing low white counts. If the white counts get too low, the immune system is compromised and the patient can easily succumb to new infections.
The second line of defense is Alkylating Agents. These perform the same type of function as the Purine Analogs, though using differing methods to create the unfavorable environment. The results are similar with similar collateral damage as well. The problem with both of these agents is that not all damaged cells are located in the blood stream. Some can be found in the spinal fluid, thus not destroyed. Other cells develop immunity to these treatments and simply refuse to die off. The result is an eventual relapse of the disease.
Enter the second form of treatment, technically not chemotherapy, but usually lumped into the same category: Monoclonal Antibodies. Reverting to the military analogy, this is much like “smart bombs”. More specifically, they are like the brave soldiers who “paint” the target with lasers so the bombs can lock on and destroy the target. These are highly targeted drugs designed to attach manmade targets to the proteins on the diseased leukocytes allowing the patients existing immune system to attack and destroy the disease. While less toxic on their own, they are often used in combination with other more toxic drugs, usually an alkylating drug.
When all of these treatments fail to bring about remission, more drastic action is needed. Enter two alternatives: clinical trials and stem cell transplant. I really have no military analogy for this. In clinical trials, patients volunteer to, in essence, become guinea pigs. They agree to use new advanced drugs or combinations of drugs which have not yet received FDA approval for general use. These drugs are administered in highly controlled environments to test the effectiveness of the drug and protect the patient. Stem cell transplants follow high dosages of chemo drugs (carpet bombing?) not only killing off the diseased cells, but the bone marrow as well. Stem cells (cells that can form into any type of cell, are then taken from a matching donor and injected into the patient who is kept under quarantine until his/her white counts are back to a sustainable level.
In the case of CLL, new trial drugs are closing in on the elusive cure. They are close and proving very promising. Research hospitals, such as MD Anderson in Houston, Texas, have refined the stem cell transplant process to produce very favorable results in qualifying patients resulting in a cure for CLL. Both treatments have their draw-backs. Patients can and have died from both, though for qualifying patients, the risk is worth taking. The alternative is much less appealing – certain death from complications, usually uncontrollable infections.