Induction therapy for acute lymphocytic leukemia (ALL) is described as a:

• A. Intensive protocol of chemotherapy in high doses to achieve remission.
• B. Long-term protocol with smaller doses of chemotherapy to achieve a cure.
• C. 2- to 5-year low-dose chemotherapy regimen to reduce painful symptoms.
• D. Combination of chemotherapy and radiation to achieve remission.

Answer: (A)

Induction therapy for ALL is an intensive, multi-agent chemotherapy given over a short period to rapidly eradicate leukemic cells and achieve remission. The goal is to clear blasts from the bone marrow and restore normal hematopoiesis, with remission typically defined by very low or absent leukemic blasts in the marrow and recovery of normal blood counts. Because ALL can spread and progress quickly, this initial phase uses high-dose, combination chemotherapy to hit the leukemic cells hard and fast, setting the stage for subsequent consolidation to eliminate any remaining disease and prevent relapse.

This fits best with describing induction as an intensive protocol of chemotherapy in high doses to achieve remission. The other descriptions point to maintenance or long-term low-dose strategies or to adding radiation, which are not the defining features of induction in ALL.