Acute Lymphoblastic Leukemia (ALL)

Overview

Acute lymphoblastic leukemia (ALL) is a fast-progressing blood cancer that occurs when lymphoid cells produced in the bone marrow multiply abnormally. The bone marrow normally produces lymphocytes, the fundamental building blocks of the immune system. In ALL, this process is disrupted: immature, non-functional lymphoblast cells multiply uncontrollably, fill the bone marrow, and block the production of healthy blood cells.

The word "acute" means the disease progresses rapidly. "Lymphoblastic" indicates which cell type is affected; these cells are the precursors of B and T lymphocytes that function in the immune system. "Leukemia" defines cancer of the bone marrow and blood.

ALL is the most common type of cancer in children. It makes up approximately 25 percent of all childhood cancers. It is seen most frequently between ages 2-5. While it is less common in adults, a rise is again observed particularly in those over 50. Hundreds of thousands of people worldwide are diagnosed with ALL every year.

The good news is this: ALL treatment in children is extremely successful. With modern treatment protocols, approximately 90 percent of children can achieve complete disappearance of the disease (full recovery). While this rate is lower in adults, results are gradually improving with the introduction of targeted therapies.

Symptoms

ALL symptoms arise from the decrease in healthy blood cells. When red blood cells decrease, anemia develops; when white blood cells decrease, susceptibility to infection occurs; when platelets decrease, bleeding problems emerge. Symptoms generally develop suddenly and rapidly and can become pronounced within weeks.

ALL symptoms include the following:

• Fatigue and pallor. Extreme fatigue related to anemia is the most common symptom of ALL. A weakness that does not go away with rest, along with lack of strength, shortness of breath, and pale skin appears. In children, not wanting to play, a drop in school performance, or a constant desire to sleep can be noteworthy signs.
• Frequent and severe infections. Non-functional white blood cells cannot protect the body from infections. Frequently recurring infections that are slow to heal or unusually severe are seen. Fever can be a symptom of both infection and the disease itself directly.
• Tendency to bleed and bruise. Small bumps lead to large bruises as platelet count falls. Excessive bleeding may occur when brushing teeth or with minor injuries. Nosebleeds, gum bleeding, and small red dots under the skin (petechiae) may be seen.
• Bone and joint pain. Pressure inside the bone increases as the bone marrow fills with lymphoblast cells. This leads to noticeable pain and tenderness especially in the legs, long bones, and breastbone. In children, this may manifest as not wanting to walk or limping.
• Lymph node swelling. Lymph nodes in the neck, armpits, groin, or inside the chest may enlarge. Swellings in the neck can be felt by hand; enlargements inside the chest can cause shortness of breath or swelling in the face.
• Abdominal swelling and fullness. A feeling of fullness or swelling in the abdominal area may be felt due to enlargement of the spleen and liver. A feeling of early satiety may occur.
• Headache, vision problems, or neurological symptoms. ALL can spread to the brain and spinal fluid. Severe and persistent headache, nausea, vomiting, blurred vision, balance problems, and numbness in the face can be signs of this.
• Fever. Fever can occur both related to infection and originating from the disease itself. Unexplained and recurring fever in particular is an important warning sign.
• Loss of appetite and weight loss. Appetite decreases due to metabolic changes and the effects of the disease. Weight loss can occur without awareness; in children, slowing of growth and development may be observed.

Many of these symptoms can overlap with other conditions. However, especially in children, the development of these symptoms together and rapidly definitely requires consulting a doctor; every day of delay matters.

When to See a Doctor

See a doctor without delay in the following situations:

• If you have unexplained fatigue that does not go away with rest
• If you are experiencing frequently recurring or non-healing infections
• If excessive bruising or bleeding is seen with minor bumps
• If unexplained fever persists
• If you notice swelling in the neck, armpit, or groin
• If bone or joint pain has become pronounced
• If a child doesn't want to play or is avoiding walking
• If you are experiencing sudden weight loss

The following symptoms require going to the emergency room:

• Very high fever and serious signs of infection
• Unstoppable bleeding
• Severe headache, confusion, or seizure
• Sudden and severe shortness of breath
• Noticeable swelling in the face or neck

ALL is a fast-progressing disease. When symptoms are noticed, seeing a doctor should happen within days.

Causes

ALL develops as a result of mutations occurring in the DNA of cells in the bone marrow. These mutations prevent cells from maturing and cause them to multiply uncontrollably. The vast majority of mutations form spontaneously throughout life and are not hereditary. However, certain factors are known to accelerate this process.

Causes that can lead to the development of ALL are as follows:

• Genetic changes. Mutations in the genes that control cell growth set the stage for uncontrolled multiplication of lymphoblasts. The t(9;22) translocation known as the Philadelphia chromosome (that is, the exchange of positions between chromosomes 9 and 22) is seen in an important subtype of ALL and directly affects treatment selection.
• Previous chemotherapy or radiotherapy. Chemotherapy or radiotherapy received for another cancer, especially those containing certain drug groups, can increase ALL risk in later years.
• High-dose radiation exposure. Nuclear accidents or exposure to high-dose radiation increases ALL risk.
• Certain viral infections. Some viruses like the Epstein-Barr virus (EBV) have been associated with certain ALL subtypes in particular.
• Genetic disorders. Genetic disorders led by Down syndrome, as well as Fanconi anemia and other genetic syndromes, significantly increase ALL risk. In children with Down syndrome, leukemia risk is 10-20 times higher compared to the general population.

Risk Factors

Risk factors for ALL are as follows:

• Childhood. ALL is seen most frequently between ages 2-5. A much better treatment response is obtained in children compared to adults.
• Male sex. ALL is seen slightly more frequently in males than females in both children and adults.
• White race. ALL is seen more frequently in white individuals compared to Black or Asian individuals; the exact reason for this is not known.
• Down syndrome or other genetic disorders. The risk of ALL is significantly increased in individuals with these syndromes.
• Previous cancer treatment. Risk increases in people who have received chemotherapy or radiotherapy.
• High-dose radiation exposure. Occupational or environmental high-dose radiation exposure increases risk.
• Certain viral infections. Some viruses like EBV have been associated with ALL development.
• Family history. A history of ALL in first-degree relatives may slightly increase risk; however, ALL is mostly not hereditary.

Diagnosis

ALL is diagnosed through clinical evaluation, blood tests, and bone marrow examination. Since it is a fast-progressing disease, the diagnostic process is also carried out rapidly.

The methods used in ALL diagnosis are as follows:

• Complete blood count (CBC). This is the first and most important step. Red blood cell, white blood cell, and platelet counts are measured. In ALL, white blood cell count can be very high, normal, or low; red blood cells and platelets are generally low. Lymphoblast cells in the blood may be visible.
• Peripheral smear. A blood sample is examined under a microscope. Lymphoblast cells are visually detected and their characteristics are evaluated. This examination strengthens the suspicion of ALL.
• Bone marrow biopsy and aspiration. This is essential for confirming the ALL diagnosis. A bone marrow sample is taken from the pelvic bone with a thin needle. The percentage of lymphoblast cells in the sample is calculated; at least 20 percent lymphoblasts in the bone marrow is required for an ALL diagnosis.
• Cytogenetic and molecular tests. The chromosomal structure and gene mutations of cells are examined. The Philadelphia chromosome (BCR-ABL fusion), TEL-AML1 fusion, and other genetic changes are critically important both for predicting the course of the disease and for determining the most appropriate treatment.
• Flow cytometry (cell surface analysis). The cell type is determined by examining the surface proteins of lymphoblast cells to find out whether the disease is B-cell or T-cell type. This distinction directly affects the treatment protocol.
• Cerebrospinal fluid (CSF) examination - lumbar puncture. Since ALL can spread to the brain, a cerebrospinal fluid sample is taken with a thin needle from the lumbar region and examined for the presence of lymphoblast cells. This examination is important for both diagnosis and treatment planning.
• Imaging methods. Computed tomography (CT) or positron emission tomography (PET-CT) may be used to evaluate lymph node enlargement, organ involvement, and the extent of the disease.
• Cardiac evaluation. Echocardiography (heart ultrasound) is performed before treatment begins due to the potential effects of chemotherapy drugs on the heart.

Treatment

ALL treatment is individualized according to the genetic subtype of the disease, the patient's age, presence of the Philadelphia chromosome, and initial response to treatment. The primary goal is to completely destroy lymphoblast cells to achieve disappearance of the disease (full recovery) and then prevent the disease from returning. Treatment is generally a process consisting of multiple phases that lasts for years.

The methods used in ALL treatment are as follows:

• Induction chemotherapy. This is the first and most intensive phase of treatment. The goal is to destroy lymphoblast cells in the bone marrow as quickly as possible and achieve complete disappearance of the disease (full response). It generally lasts four to six weeks and involves a combination of multiple chemotherapy drugs; vincristine, corticosteroids, anthracycline group drugs, and asparaginase are the most commonly used. The patient is followed as an inpatient during this intensive treatment.
• Consolidation (intensification) therapy. This is the treatment phase applied after the disease has completely disappeared, to clean out remaining leukemia cells that may still be in the body but cannot be seen with the naked eye. High-dose methotrexate, cytarabine, and other drugs are used in this phase. It can last several months.
• Central nervous system (brain) protection treatment. Since ALL tends to spread to the brain, a special treatment targeting the brain is applied. Direct delivery of medication into the spinal fluid (intrathecal chemotherapy) and sometimes brain radiotherapy are used for this purpose. This step is an indispensable part of treatment.
• Maintenance (protective) therapy. After the other phases are completed, low-dose chemotherapy is continued for generally two to three years to prevent the disease from returning. 6-mercaptopurine and methotrexate are the most commonly used drugs. During this phase, the patient can mostly continue their daily life.
• Targeted therapies. When genetic tests reveal specific mutations, drugs that directly target these mutations are added to the treatment. The most important example is Philadelphia chromosome-positive ALL: in these patients, tyrosine kinase inhibitors such as imatinib, dasatinib, or ponatinib are added to chemotherapy, significantly increasing treatment success. These drugs stop leukemia cells from multiplying by blocking the abnormal protein.
• Immunotherapy. These are treatments that mobilize the immune system against leukemia cells. Blinatumomab is a drug that brings two different cells together, enabling immune cells to recognize and destroy leukemia cells. Inotuzumab ozogamicin is a targeted drug that binds to the surface of leukemia cells and leaves a toxic substance inside them. These treatments are used especially in patients who don't respond to standard chemotherapy or whose disease has returned.
• CAR-T cell therapy. This is an advanced treatment method in which the patient's own immune cells (T cells) are reprogrammed in the laboratory to recognize leukemia cells and then given back to the patient. Tisagenlecleucel (Kymriah) is a CAR-T treatment approved for children and young adults. It is showing promising results in ALL that has returned or has not responded to two or more treatments.
• Allogeneic stem cell transplant (bone marrow transplant). This is applied in high-risk ALL or when the disease returns. Stem cells taken from a healthy donor are transplanted to the patient. The transplanted donor immune cells recognize remaining leukemia cells in the body as foreign and destroy them; this is called the graft-versus-leukemia effect. This treatment is a powerful option with the potential to completely cure the disease; however, it carries serious risks including infection, immune system reactions (graft-versus-host disease, where the donor's immune cells attack the patient's healthy tissues), and damage to organs. Finding a suitable donor can also extend the process.
• Clinical trials. ALL research is advancing rapidly. New targeted drugs, new immunotherapy combinations, and improved CAR-T approaches are being tested in clinical trials. For suitable patients, participation in clinical trials can provide access to new and promising treatments beyond standard therapy.

Complications

ALL itself and its treatment can lead to various complications.

Complications that may be seen in ALL are as follows:

• Serious infections. Both the disease itself and chemotherapy-related suppression of the immune system set the stage for serious bacterial, fungal, and viral infections. Fever during the period when immunity is at its lowest (neutropenic fever) is a situation requiring emergency intervention and antibiotics must be started rapidly.
• Bleeding problems. Low platelet count increases the risk of internal bleeding. Brain bleeding is one of the most serious and rare complications.
• Brain involvement. ALL can spread to the brain and spinal fluid. It can lead to severe headache, seizures, and altered consciousness. For this reason, protective treatment targeting the brain is applied to all patients.
• Tumor lysis syndrome. When chemotherapy is started, large numbers of leukemia cells break down rapidly and their contents enter the bloodstream. This can cause kidney failure, cardiac arrhythmias, and muscle cramps. It can largely be prevented with adequate fluid intake and medication.
• Damage to organs from medications. Chemotherapy drugs can affect the heart, liver, kidneys, and nervous system. Anthracycline group drugs can weaken the heart muscle in the long term. Methotrexate at high doses can affect the kidneys and nervous system. For this reason, regular organ monitoring is carried out during and after treatment.
• Relapse (disease returning). This is ALL reappearing after treatment. Risk is higher especially in the first two years. In ALL that has returned, salvage chemotherapy, immunotherapy, CAR-T therapy, and stem cell transplant are considered.
• Stem cell transplant complications. The most important problem after transplant is graft-versus-host disease, where the donor's immune cells attack the patient's healthy tissues. Post-transplant infections and damage to organs from medications are also among the important risks.
• Long-term late effects. Especially in children, intensive chemotherapy and brain radiotherapy can lead to learning difficulties, growth delays, hormonal problems, and risk of secondary cancer in later years. For this reason, children who survive ALL are followed with long-term monitoring programs.
• Psychological effects. The long and difficult treatment process, extended time spent in hospital, and uncertainty can lead to depression, anxiety, and post-traumatic stress disorder. Both patient and family should receive support in this regard.

Living with ALL

An ALL diagnosis can change life overnight for the patient, family, and loved ones. Especially for child patients and their parents, this process is extremely intense both physically and emotionally. However, with the right support it is possible to manage this difficult process better.

Physical Care During Treatment

Since the immune system is significantly suppressed during and after induction chemotherapy, protecting against infections becomes the top priority. During this period when the immune system is at its weakest, even a simple cold can pose a serious threat.

Hand hygiene is one of the most important things that can be done during this process. Patients and family members developing the habit of frequent and correct handwashing significantly reduces the risk of catching infections. Asking visitors to show the same care is also important for both the patient and those around them. Close contact with sick or infected people should be avoided.

Nutrition directly affects the treatment process. Eating enough can become difficult due to nausea, loss of appetite, and taste changes. Preferring small but frequent meals, turning toward high-protein foods, and adequate fluid intake both help maintain energy levels and protect the kidneys. Meeting with a nutritionist allows a personalized plan to be created.

Oral care gains special importance during the chemotherapy period. Chemotherapy can damage the oral mucosa and lead to painful mouth sores (mucositis). Using a soft toothbrush, gargling several times a day with alcohol-free mouthwash, and maintaining the oral care routine the doctor recommends reduces this risk. If mouth sores or painful swallowing develop, they should be reported immediately.

For Child Patients and Parents

Since ALL is the most common cancer in children, this experience is also extremely shattering for parents. Explaining the disease to your child in age-appropriate language helps reduce both their anxiety and yours. Approaching a child who asks "Why me?" honestly but with hope is important.

Long hospital processes can disrupt school life. Many hospitals provide pedagogical support; through educational coordinators, children can continue learning even during treatment. Preparing the back-to-school plan together with teachers and school counselors after discharge facilitates the child's social adjustment.

Siblings and other family members are also deeply affected by this process. It is important to keep in mind that siblings may feel neglected and may experience jealousy or guilt. Family therapy can help all family members cope in a healthy way during this process.

Coping Emotionally

Hearing a "cancer" diagnosis can be devastating. Shock, fear, anger, sadness, and denial are completely normal and expected reactions. Rather than trying to suppress these feelings, sharing them with trusted people or a professional is much healthier.

Don't hesitate to seek support from an oncology psychologist or psychiatrist. Depression and anxiety disorder are common effects of both the disease and the treatment; treating them strengthens overall wellbeing and adherence to treatment. Psycho-oncology support is offered at many cancer centers.

Accepting support from family and friends can be difficult. Saying "yes" to "Can I help?" may seem hard, but practical help like bringing food, dropping children off at school, or accompanying to hospital makes a big difference. Telling those around you clearly how they can help both reassures them and enables genuine sharing of the burden.

Connecting with other ALL patients and survivors can be empowering. Support groups offer both practical knowledge and emotional solidarity. Someone sharing their own experience is the person who understands you best.

Managing Chemotherapy Side Effects

Nausea and vomiting are among the most frequently seen side effects. Modern anti-nausea medications can largely bring these symptoms under control. Keeping in mind that strong smells can trigger nausea, preferring cold or room-temperature foods, and taking small frequent meals helps you get through this period more comfortably.

Fatigue is one of the most challenging aspects of the chemotherapy process and is different from ordinary tiredness; it may not go away with sleep and can seriously restrict daily life. Saving your energy for the most important activities, planning rest breaks, and continuing with tolerable activities like light walking helps with managing fatigue.

Hair loss is a temporary side effect of some chemotherapy drugs. Hair generally grows back within a few months after treatment ends. However, this change in appearance can be emotionally difficult for both children and adults. Researching wig, hat, or scarf options before chemotherapy begins can be a step that helps you feel more prepared.

After Remission and Long-Term Follow-up

After the disease has completely disappeared, the process doesn't end. Maintenance therapy, regular blood tests, and bone marrow checks continue for years. These checks are critically important for monitoring whether the disease returns in the early period.

Children in particular need careful monitoring for long-term side effects. Learning and attention difficulties, growth and hormonal problems, and rarely secondary cancer risk can be managed by early detection. Specialized long-term follow-up clinics for ALL survivors maintain this monitoring systematically.

Heart health should also be closely monitored. Anthracycline group chemotherapy drugs can affect the heart muscle years later. Regular cardiology checkups allow this risk to be caught early.

Chemotherapy and radiotherapy can affect fertility. Discussing egg or sperm freezing options with your doctor before treatment is an important step for the years ahead.

For Family and Caregivers

ALL treatment is an extremely difficult process not only for the patient but also for all family members. Long times spent in hospital, financial burden, and uncertainty can be draining.

Don't neglect your own care. Caregiver burnout is a real and serious condition. Adequate sleep, regular nutrition, and short breaks maintain both your productivity and health. Don't hesitate to seek support from a social worker or psychologist if needed.

Establish open communication with the hospital team. Don't hesitate to ask anything you're curious about. Being informed about the treatment plan, expected side effects, possible risks, and long-term expectations empowers both you and the patient. Don't let anything you don't understand get glossed over.

In Case of Relapse

Learning that the disease has returned can be as shattering as the initial diagnosis, or even more so. However, treatment options exist even in this situation. Salvage chemotherapy, immunotherapy, CAR-T cell therapy, and stem cell transplant can be considered. Applying to a center experienced specifically in ALL and researching clinical trial options is an important step in this process.

Preparing for Your Appointment

What you can do:

• Note in detail when symptoms started and how they progressed
• If you have previously received cancer treatment, specify which drugs you received and if radiotherapy was applied, the area and dose
• Share if there is a history of blood cancer or genetic syndrome in the family
• List all medications, vitamins, and supplements you are taking
• For a child patient, bring the growth and development tracking booklet and vaccination card
• Write your questions in order of priority; appointment time may be limited

Questions you can ask your doctor are as follows:

• What subtype and genetic profile does my ALL have?
• Is the Philadelphia chromosome positive?
• What is my (or my child's) risk group?
• What is the recommended treatment plan and why this plan?
• Will a bone marrow transplant be needed?
• Is CAR-T therapy or a clinical trial a suitable option?
• How will the brain-directed treatment be applied?
• What long-term side effects are possible?
• What can I do to preserve my fertility?
• Can my child continue school during treatment?
• What is the risk of the disease returning and how will we follow up?

Questions your doctor may ask you are as follows:

• When did symptoms start and how did they progress?
• Have you previously been diagnosed with cancer and received treatment?
• Have you received chemotherapy or radiotherapy in the past?
• Is there a history of blood cancer or genetic disease in the family?
• Is there Down syndrome or another genetic disorder?
• How is your general health, do you have other illnesses?
• Which medications do you use regularly?
• Are you thinking about having children?