OBJECTIVES: Cure rates improve when adolescents and young adults with acute lymphoblastic leukemia (ALL) are treated according to pediatric protocols. Assumed risks of toxicities and associated delays in treatment have played a role in setting upper age limits. The aim of this study was to examine the toxicity profile and treatment delays in NOPHO ALL2008 comparing children and adults.

METHODS: We collected information on 19 treatment-related toxicities, systematically captured at 3-month intervals throughout therapy, and time intervals between 12 consecutive treatment phases for 1076 patients aged 1-45 yrs treated according to the Nordic/Baltic ALL2008 protocol.

RESULTS: No adults died during induction. The duration of induction therapy and postinduction treatment phases did not differ between children and adults, except for patients 18-45 yrs being significantly delayed during two of nine high-risk blocks (median number of days for patients 1-9, 10-17, and 18-45 yrs; the glucocorticosteroid/antimetabolite-based block B1: 24, 26, and 29 d, respectively, P = 0.001, and Block 5 (in most cases also a B block): 29, 29, and 37 d, respectively, P = 0.02). A higher incidence of thrombosis with increasing age was found; highest odds ratio 5.4 (95% CI: (2.6;11.0)) for patients 15-17 yrs compared with children 1-9 yrs (P < 0.0001). Risk of avascular osteonecrosis was related to age with the highest OR for patients 10-14 yrs (OR = 10.4 (95% CI: (4.4;24.9)), P < 0.0001).

CONCLUSION: Adults followed and tolerated the NOPHO ALL2008 protocol virtually as well as children, although thrombosis and avascular osteonecrosis was most common among adolescents.