chronicphase

Chronic phase is a term used in medicine to describe a stage of a disease that persists for a long duration and progresses slowly. It contrasts with the acute phase, which denotes rapid onset and often severe symptoms. In many conditions, the chronic phase follows an initial acute event or represents a long-standing, partially controlled disease state. Characteristics typically include longer duration, milder or intermittent symptoms, and ongoing risk of organ involvement or systemic effects despite apparent stability. Treatment goals usually focus on control of symptoms, prevention of progression, and management of complications, often requiring long-term therapy, monitoring, and lifestyle adjustments.

In chronic myeloid leukemia (CML), chronic phase (CP-CML) is the initial phase of the disease. It is characterized by persistent leukocytosis with predominantly mature granulocytes, basophilia, and fewer than 10% blasts in blood or bone marrow. Patients may be asymptomatic or have nonspecific symptoms such as fatigue or splenomegaly. Diagnosis relies on blood counts, bone marrow examination, and detection of the BCR-ABL1 fusion gene from t(9;22). Treatment with tyrosine kinase inhibitors (TKIs) has transformed prognosis; first-line imatinib and later-generation TKIs aim to induce hematologic, cytogenetic, and molecular responses. Most patients stay in CP for years with effective therapy, but progression to accelerated phase or blast crisis may occur if disease is not adequately controlled. Monitoring includes regular complete blood counts, cytogenetic analysis, and measurement of BCR-ABL1 transcript levels; response guides treatment decisions, including switching TKIs. In selected patients, allogeneic stem cell transplantation may be considered for advanced disease or TKI-resistant cases.

Other diseases may also describe a chronic phase stretching over months to years, including other hematologic cancers and chronic infectious or inflammatory diseases, where the term denotes long-term management rather than cure.