Mediastinal Mass with Bone Marrow Involvement Is a Favorable Factor for Childhood T-Lymphoid Malignancy in Japan.

T-cell acute lymphoblastic leukemia (T-ALL) and T-cell lymphoblastic lymphoma (T-LBL) account for most of the childhood T-lymphoid malignancy(LM). T-ALL is usually treated by the same protocol to the B-progenitor ALL. It is obvious that biologically, T-cell behaviors are different from those of B-progenitor cell, and cell origins are same among T-ALL and T-LBL. Thus we conducted a strategy initiating T-ALL specific protocol, differing from protocols for B-progenitor ALL. Furthermore, we indicated the same protocol to advanced T-LBL. The aims of this study were to evaluate the efficacy and safety of indicating the same protocol for childhood T-ALL and advanced T-LBL, and to reveal the prognostic factors of childhood T-LM. 70 eligibleT-ALL patients enrolled in the JACLS ALL-97 study between 1997-2001, and 32 eligible patients with stage III and IV T-LBL enrolled in the JACLS NHL-T98 trial between 1998-2002 were analyzed. Median age was 9y8m (2y~15y3m) for T-ALL and 11y11m (3y~15y4m) for T-LBL. Male/female ratio was 46/24, 26/6, respectively. Mediastinal mass was found in 31/70(44.3%) for T-ALL, 19/21(90.5%) for stageIII and 6/11(54.5%) for stageIV T-LBL. The treatment for 2 years consisted of the induction therapy (VCR, HD-MTX, CA, PSL, ASP), the 5-drug consolidation therapy A and B, both including high dose of ASP, and maintenance therapy with block-rotated treatment using drugs above. Complete remission(CR) at the end of induction therapy was obtained 65/70(92.9%) for T-ALL, 15/21(71.4%) for stage III and 10/11(90.9%) for stage IV T-NHL. 5-year overall survival(OAS) rate for T-ALL, stage III and stage IV T-LBL was 81.1%, 63.9% and 81.8%, respectively. 5-year event free survival (EFS) rate was 72.9%, 47.6% and 72.3%, respectively. Relapse after CR occurred in 12/65 with T-ALL, 6/15 with stage III and 1/10 with stage IV T-LBL. Single variant analysis revealed that there were no significant difference in OAS or EFS for T-ALL patients based on WBC, NCI index, but statistical difference in OAS or EFS based on age(older than 10y worse), the existence of mediastinal mass(absence, worse) In T-LBL, there were no statistical differences based on age, existence of mediastinal mass. Multivariate analysis revealed, for T-ALL and T-LBL patients as a whole, that age > 10 years was a risk factor in both OAS and EFS, absence of mediastinal mass and stage III T-LBL were risk factors in OAS. Our data shows that indicating same T-cell specific protocol, for T-ALL and advanced T-LBL has a potential to improve the prognosis of T-LM. The older age, and stage III T-LBL appeared as prognostic factors. Moreover, mediastinal mass with bone marrow involvement was a favorable factor for childhood T-LM. Although some risk factors were documented, it is needed to clarify unknown prognostic factors and develop the more effective, stratified T-cell specific protocols.