Acute Lymphoblastic Leukemia (ALL) is a kind of blood cancer which involves the rapid formation and accumulation of immature white blood cells (WBCs) known as lymphocytes in the bone marrow. From the bone marrow, these malignant cells quickly invade into the blood and spread to other organs such as the lymph nodes, liver, spleen, brain, spinal cord, or testicles. Due to its ‘acute’ nature, ALL progresses fast and thus needs to be treated immediately or else can prove fatal in few months. Though it can affect any age group, but is most commonly found in children.
ALL is broadly classified as follows:
- L1 – subtype represents 25-30% of adult cases
- L2 – subtype represents 70% of cases (most common)
- L3 – subtype represents 1-2% of adult cases
Signs and symptoms of Acute Lymphoblastic Leukemia (ALL)
- Signs of anemia, such as pale appearance, palpitations, fatigue, dizziness, and difficulty in breathing (dyspnea) from even mild exertion
- Easy bruising and bleeding like nose bleeds, bleeding gums
- Shortness of breath
- Recurring infections
- Palpable lymph nodes
- Severe bone pain
- Headache, vomiting, blurred vision or seizures, in case the cancer has spread to the brain
- Full and swollen belly
- Renal failure in patients with a high tumor burden
- Petechiae (red or purple spot on the skin, caused by a minor bleed from broken capillary blood vessels) and ecchymoses (a skin discoloration resulting from bleeding underneath)
- Signs relating to organ infiltration with leukemic cells and lymphadenopathy
Diagnostic Tests for ALL
Include complete blood count with differential, coagulation studies, peripheral blood smear, chemistry profile, including lactic dehydrogenase, uric acid, liver function studies, and BUN/creatinine, and blood cultures
Bone marrow aspiration
A bone marrow aspiration is required to look for leukemia cells. Its purpose is to classify blood cells into specific types and observe the changes in the cancerous cells. The study is helpful in devising a treatment plan of the ALL patient.
Other blood/bone marrow tests
Immunophenotyping, Flow cytometry, Cytogenetics, Polymerase chain reaction, Gene expression profiling
Lumbar puncture test
This test is done to check the spread of blood cancer cells in the brain.
These tests include X-ray, computerized tomography (CT) scan, and ultrasound to rule out any other organ infection.
Treatment of Acute Lymphoblastic Leukemia (ALL)
The standard treatment plan for ALL is usually the combination of chemotherapy and radiation therapy along with the bone marrow transplant. The survival rates of ALL vary by age – 85% in children and 50% in adults.
It has been found only 20-30% of adults are cured with standard chemotherapy treatment. Generally, more than 80% adults with ALL will have complete remissions from leukemia cells during their treatments. But unfortunately, ALL may relapse in about half of these patients. It is also important to note, younger patients respond better to the blood cancer treatment than older ones.
ALL cancer treatment can be broadly divided into four main phases, which may last for about three years:
Induction therapy phase: Its goal is to kill most of the leukemia cells in the blood and bone marrow and restore normal blood cell production.
Consolidation therapy or post-remission therapy phase: Post-induction therapy when remission is achieved, treatment is done to kill the remaining malignant cells in the body and prevent relapse. This is the consolidation phase.
Maintenance therapy phase: The purpose of this next phase of ALL treatment is to prevent regrowth of malignant cells and it may continue for over years.
CNS prophylaxis or Intrathecal chemotherapy: It is a preventive treatment in which chemo drugs are given to destroy leukemia cells present in the brain and spinal cord.
Treatments given during above phases include:
Chemotherapy: In chemotherapy drugs are given to patients to kill blood cancer cells.
Targeted drug therapy: As the name suggests, targeted drugs attack specific abnormalities in cancer cells, thereby preventing them to grow. Administered during or after chemotherapy, it is given to patients having gene abnormality called the Philadelphia chromosome.
Radiation therapy: High-powered beams are used to kill cancer cells.
Stem cell or Bone Marrow Transplant (BMT)
It is given to those who are at high risk of relapse or when the leukemia has relapsed. . A bone marrow transplant is accompanied by chemotherapy or radiation.
The Acute Lymphoblastic Leukemia patient may require an allogenic bone marrow transplant, i:e., a matching donor’s bone marrow for transplant.
Most authorities agree that allogeneic transplant should be offered to young patient with high-risk features (Philadelphia chromosome–positive (Ph+) whose ALL is in first remission. Young patients without adverse features should receive induction, consolidation, and maintenance therapy. In these patients, BMT is reserved for relapse.
Previously, patients with mature B-cell ALL would have been referred for transplantation when their disease was in first complete remission (CR) phase; however, with improving results from more intensive chemotherapy regimens, many clinicians are reserving BMT for patients who have experienced relapse.
Hematopoietic stem cell transplantation (HSCT) seems to be a valuable option for a subgroup of infants with mixed-lineage ALL carrying poor prognostic factors that include age younger than six months and either poor response to steroids at day 8 or leukocyte levels of 300 g/L or higher. HSCT may be autologous, allogeneic or syngeneic (from identical twin).
The ALL patients undergoing allogenic BMT, the rate of freedom from relapse was 70% at 4 years. However, because of transplant-related complications, the event-free survival rate was only 33%. No toxic deaths occurred in the subjects who underwent autologous BMT. However, the event-free survival rate was only 17% at 4 years because of a high rate of relapse.