Leukemia is a type of cancer that originates in the blood-forming tissues, most commonly the bone marrow. This condition involves the rapid production of abnormal white blood cells, which do not mature properly and can crowd out healthy blood cells. These dysfunctional cells interfere with the body’s ability to fight infection, carry oxygen, and clot blood. A primary goal of leukemia treatment is to achieve remission, which signifies a positive response to therapy and a reduction in the presence of cancer cells.
Understanding Remission
Remission in leukemia indicates that the signs and symptoms of the disease have lessened or disappeared following treatment, signifying the cancer is under control with significantly reduced or absent visible evidence. This outcome is usually the result of treatments such as chemotherapy, radiation therapy, or targeted therapies. During remission, patients often experience a reduction or cessation of symptoms like fatigue, fevers, and bruising. The duration of remission can vary, potentially lasting for months, years, or even the remainder of a person’s life. While a highly desirable goal, remission does not automatically mean the cancer has been completely eliminated from the body.
Levels of Remission
Medical professionals classify remission into different categories based on the extent of cancer reduction and the body’s recovery. Complete Remission (CR), also known as complete response, occurs when there is no detectable evidence of leukemia through physical exams, blood tests, or imaging. For a patient to be in complete remission, less than 5% of their bone marrow cells should be abnormal blasts, and their blood cell counts, including white cells, red cells, and platelets, should return to normal levels.
Partial Remission (PR) means the cancer has responded to treatment, but some signs of the disease remain. This indicates a significant reduction in cancer cells, though not enough for complete remission. Complete Remission with Incomplete Hematologic Recovery (CRi) means that while the percentage of blasts in the bone marrow is less than 5%, some healthy blood cell counts, such as neutrophils and platelets, have not fully returned to normal levels.
A more precise level of remission is known as molecular remission or minimal residual disease (MRD) negativity. This status means that even with highly sensitive tests, no leukemia cells can be detected in the body. These advanced tests detect extremely small numbers of cancer cells missed by standard methods, providing a deeper assessment of disease burden. Achieving MRD negativity is often associated with a lower risk of relapse and better long-term outcomes.
Confirming Remission
Confirming remission in leukemia involves a series of diagnostic procedures and laboratory tests. Doctors regularly perform blood tests, such as a complete blood count (CBC), to check for normal levels of red blood cells, white blood cells, and platelets. The absence of leukemia cells in the peripheral blood is an initial indicator of treatment success.
A bone marrow biopsy is a procedure for assessing remission status, as leukemia originates in the bone marrow. During this test, a small sample of bone marrow is taken, typically from the hip bone, to examine the percentage of abnormal cells (blasts) present. For complete remission, the bone marrow should show less than 5% blasts. This test is performed at diagnosis and at various points during and after treatment to monitor response.
More sensitive techniques are utilized to detect minimal residual disease (MRD), which can be present even when a patient is in complete remission by conventional standards. Flow cytometry identifies leukemia cells based on specific markers on their surface, detecting as few as 1 leukemic cell in 1,000 to 10,000 normal cells in acute myeloid leukemia (AML) or up to 1 in 10,000 normal cells in acute lymphoblastic leukemia (ALL). Polymerase Chain Reaction (PCR) testing is another highly sensitive method that looks for specific genetic alterations or mutations unique to the leukemia cells. PCR can detect one cancer cell among 100,000 to 1 million normal cells, offering a detailed assessment of remission depth.
Remission Versus Cure
It is important to distinguish between remission and a cure in the context of leukemia. While remission signifies the disappearance or significant reduction of disease signs, it does not always equate to a complete eradication of all cancer cells. Even if tests show no evidence of disease, a small number of leukemia cells might remain undetected in the body. These lingering cells have the potential to grow and cause the cancer to return, a situation known as a relapse.
This means ongoing vigilance and continued medical follow-up are often necessary even after achieving remission. For some patients, maintenance therapy—lower doses of medication—may be continued for months or years to help keep the cancer from returning. This distinction highlights the need for continued monitoring and personalized care plans to manage the disease long-term.