Localized Lymphoblastic Lymphoma in Children and Adolescents: Results of the LLB-NHL03 Trial-A Report From the Japan Children's Cancer Group.

Abstract

Background: Localized lymphoblastic lymphoma (LL) is rare in pediatric patients. The best treatment for patients with localized LL remains to be determined because of the rarity of the disease.

Methods: Between November 2004 and October 2019, 41 newly diagnosed patients up to 18 years of age with localized LL (Murphy stages I and II) were enrolled in the LLB-NHL03 trial. The treatment consisted of five phases: induction, consolidation, central nervous system prophylaxis, delayed intensification, and maintenance. The total duration of therapy was 24 months from the time of diagnosis.

Results: Of the 41 patients, six patients were excluded with a different diagnosis; therefore, 35 were included in the primary efficacy and safety analysis. The mean age at diagnosis was 9.2 years (range 2.1-16.1 years). Sixty-five percent of patients were male. Twenty-nine patients had a pre-B immunophenotype, and six had a pre-T immunophenotype. The head and neck area accounted for 66% of the primary sites. At a median follow-up of more than 10 years, the 3-year event-free survival rate [95% confidence interval] was 97.1% [81.4-99.6%], and the 3-year overall survival rate was 100%. Overall, patients tolerated the therapy well, and no treatment-related deaths were observed.

Conclusion: This is the largest clinical trial conducted exclusively in children with newly diagnosed localized stage LL. The outcomes of pediatric patients with localized LL treated with 2 years of acute lymphoblastic leukemia-type therapy, which is characterized by a relatively low anthracycline dose, exclusive use of prednisolone steroids, and fewer intrathecal therapies compared with previous studies, were excellent.

Clinical trial registration number: This trial was registered in the Japan Registry of Clinical Trials (jRCT): jRCTs041180131.