Importance: The incidence of acute lymphoblastic leukemia (ALL) and lymphoblastic lymphoma (LBL) in adolescent and young adult (AYA) patients (age range, 15-39 years) in the United States is increasing at a greater rate than in younger or older persons. Their optimal treatment has been increasingly debated as pediatric regimens have become more widely used in the age group. This review compares the basic features of pediatric and adult chemotherapy regimens for ALL and LBL, recognizes and describes the challenges of the pediatric regimen, and suggests strategies to facilitate its adoption for AYAs with ALL and LBL.
Observations: All but 2 of 25 published comparisons of outcomes with pediatric and adult regimens for ALL and LBL in AYAs and 1 meta-analysis favor the pediatric regimen. After more than a half-century of clinical trials of the pediatric regimens, including at least 160 phase 3 trials in the United States, the pediatric regimens have become far more complex than most adult regimens. Asparaginase, a critical component of the pediatric regimens, is more difficult to administer to AYAs (and older patients) but nonetheless has a favorable benefit to toxicity ratio for AYAs. A dramatic reduction in outcome of ALL and LBL during the AYA years (the "survival cliff") is coincident with similar reductions in proportions of AYAs referred to academic centers and enrolled on clinical trials (the "accrual cliff" and "referral cliff").
Conclusions and relevance: The accumulating data increasingly support treating AYAs with ALL and LBL with a pediatric-inspired regimen or an approved institutional or national clinical trial tailored for this patient group. A need to develop clinical trials specifically for AYAs and to encourage their participation is paramount, with a goal to improve both the quantity and quality of survival.