[Clinical study of 131 children with multi-system Langerhans cell histiocytosis]

To analyze the clinical characteristics and treatment outcome of children with multi-system Langerhans cell histiocytosis (MS-LCH).

From January 2007 to December 2013, newly diagnosed patients with histopathologically-confirmed MS-LCH were enrolled in this retrospective study. All patients were treated on the Shanghai Children's Medical Center LCH protocol (LCH-Ⅱ modified protocol). Survival was determined using the Kaplan-Meier method with differences between different groups compared using the Log-Rank test. Prognostic relevance of different parameters were analyzed by Cox proportional hazard model.

Of the 131 patients (86 boys and 45 girls), the median age was 3 years (range 3 months to 14 years). Rapid response at week 6 was achieved in 79% (104/131) evaluable patients and 74% patients (48/65) with risk organ involvement. The 3-year event free survival (EFS) and 3-year overall survival (OS) for all cases were (62±5)% and (82±4)%. The 3-year OS was significantly different between age at diagnosis ≤2 years and >2 years group.The 3-year OS was also significantly different between patients with and without risk organ involvement.The 3-year OS of patients who had rapid response at week 6 was significantly higher than that of those without rapid response (χ(2) =12.600, 11.583, 38.711; P=0.000, 0.001, 0.000). Cox regression analysis showed that risk organ involvement and poor response at week 6 were the most important prognostic factors for patients with MS-LCH (OR=12.352, 14.356; P=0.001, 0.000). However, age was not the independent prognostic risk factor (OR=1.013, P=0.207). There were 36 patients (28%, 36/131) who experienced disease progression or relapse. The time to disease progression or relapse ranged from 1 to 25 months from the initial diagnosis (median 11 months). Significantly lower OS (18±3)% was observed in 20 patients with risk organ involvement at progression or relapse. Patients with poor response at week 6, younger age or risk organ involvement at diagnosis was associated with disease progression/relapse (χ(2)=15.747, 7.289, Z=3.865; P=0.000, 0.007, 0.000).

Risk organ involvement and poor response at week 6 are the strongest prognostic factors for patients with MS-LCH. Second initial treatment for patients with poor response at week 6 and effective salvage therapy need to be taken into account in our future studies.