## Acute Lymphoblastic Leukemia (ALL): Prognostic and Treatment Features **Key Point:** Philadelphia chromosome t(9;22) is the MOST COMMON cytogenetic abnormality in adult ALL (present in ~20–25% of adult ALL), NOT in young adults aged 28 years. In pediatric ALL, t(9;22) is less common (~3–5%), and other translocations like t(12;21) are more frequent. ### Cytogenetic Abnormalities in ALL by Age | Abnormality | Frequency in Children | Frequency in Adults | Prognosis | |-------------|----------------------|-------------------|----------| | **t(12;21) ETV6-RUNX1** | 20–25% | <5% | Favorable | | **Hyperdiploidy (>50 chr)** | 25–30% | 10% | Favorable | | **t(9;22) Philadelphia** | 3–5% | 20–25% | Unfavorable | | **t(1;19) TCF3-PBX1** | 5% | <5% | Intermediate | | **t(4;11) KMT2A-AFF1** | 5–10% | 10% | Unfavorable | **High-Yield:** In a 28-year-old woman with ALL, t(12;21) and hyperdiploidy are MORE common favorable-risk features than t(9;22). The statement that t(9;22) is "the most common" in this age group is INCORRECT. ### CD10 Positivity: Common ALL (cALL) - **CD19+ CD10+** = common ALL (cALL) - Represents ~80% of pediatric B-ALL - Generally favorable prognosis in children - Better response to chemotherapy ### High WBC Count as Adverse Prognostic Factor **Clinical Pearl:** WBC >30,000/μL (or >100,000/μL in some systems) at presentation is an independent adverse prognostic factor in ALL, associated with: - Higher tumor burden - Increased risk of leukostasis - Worse event-free survival ### Standard Induction Therapy for ALL 1. **Vincristine** (weekly IV) 2. **Daunorubicin** (or doxorubicin) (IV) 3. **L-asparaginase** (IV or IM) 4. **Corticosteroids** (prednisone or dexamethasone) **Mnemonic:** **VALD** = **V**incristine, **A**sparaginase, **L**eukeran (chlorambucil), **D**aunorubicin (though modern regimens use corticosteroids instead of chlorambucil). This is the backbone of ALL induction therapy worldwide.
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