All you need to know about: Chronic Lymphocytic Leukemia (CLL)

A typical “smudge cell” on a peripheral blood smear, a common finding in patients with chronic lymphocytic leukemia (CLL) | Photo Credit: By Mikael Häggström, https://commons.wikimedia.org/w/index.php?curid=114453624 Chronic lymphocytic leukemia (CLL) is a type of leukemia or blood cancer that affects the blood and bone marrow (spongy tissue inside the bones that forms blood cells). It is one of the lesser-known types of blood cancers in India. . According to a 2025 paper published in the European Society of Medicine, CLL is one of the least common leukemias in India, accounting for less than 5% of all leukemias, with incidence rates ten times lesser than in the United States. What is CLL? The term ‘lymphocytic’ refers to the particular cells that are affected by this type of leukemia. In this condition the lymphocytes or group of white blood cells in the body exceed the normal count and increase in abnormal quantities inside the patient’s body. The white blood cells form part of the immune system and help the body fight diseases. When the body contracts an infection, the white blood cell count increases, in a defence mechanism to fight against the infection. As the infection gets better, the white blood cell count decreases. But when a person has CLL, the number of white blood cells do not subside even after an infection leaves the body. CLL has a slower prognosis in the human body than other types of leukemia. According to doctors, CLL does not have any specific cause. . Doctors said most cases of CLL are not linked to environmental exposure, and are believed to arise from inherent oncogenic changes. How is CLL diagnosed? According to Aseem Kumar Samar, director - medical oncology, C.K. Birla Hospitals Jaipur, CLL is a type of cancer that is sometimes discovered by chance during a regular blood check, in particular if lymphocyte counts are abnormally high. To diagnose this condition a complete blood count and a peripheral blood film (smear) are the first steps. Blood cell analysis by flow cytometry is key to confirm the disease as this test reveals the typical abnormal B-lymphocytes present in CLL. “Based on the individual situation, other tests, for example, fluorescence in situ hybridisation (FISH), TP53 mutation analysis and immunoglobulin heavy-chain variable region (IGHV) testing -- all genetic tests -- will be done to understand the disease better, make plans and give a prognosis. In some cases doctors may ask for CT scans,” Dr. Samar added. According to experts, a bone marrow test is usually not a must for a proper diagnosis, but it can be done if there are certain reasons to justify it or if the doctor deems fit. Symptoms and prognosisCLL is usually asymptomatic initially, and presents an increased lymphocyte count, according to Rajib De, head – clinical haematology, haemato-oncology & BMT, Manipal Hospital, EM Bypass, Kolkata. “As the disease progresses, patients may develop swollen lymph nodes, weakness, weight loss and fever, followed in later stages by anaemia and low platelet counts,” Dr. De said. CLL is broadly classified into Stage A, B and C, with Stage A being asymptomatic, Stage B involving lymph node swelling, and Stage C presenting with symptoms such as weakness, anemia and low platelets. Treatment for CLLTreatment for CLL depends on the stage of disease, symptoms, overall health, and specific genetic and molecular characteristics. Many patients with early, asymptomatic CLL do not require immediate treatment and can be safely monitored with a ‘watch and wait’ policy and regular blood tests and clinical evaluations. Subhasish Chatterjee, who was diagnosed five years ago, said he has not been under any treatment. He only has regular checkups at the Tata Medical Centre - Cancer Hospital & Research Center in Kolkata. “I do blood tests and visit the doctor every six months, and I take a flu vaccine every year in March as a precautionary measure against infections, as was prescribed by the doctors. The doctor has not suggested any other treatment till my blood parameters remain the same,” said the 62-year-old. Mr Chatterjee was detected with CLL incidentally, after going for a check-up following a bout of Covid-19 in 2021. When treatment becomes necessary, targeted oral therapies such as BTK inhibitors and BCL2 inhibitors, sometimes combined with anti-CD20 antibodies, are commonly used. The choice of therapy is increasingly guided by molecular markers such as TP53 abnormalities. Treatment is individualised, with the goal of controlling the disease effectively while maintaining quality of life and minimising treatment-related side effects, Dr. Samar said. Published - August 31, 2026 03:30 pm IST