Treatment Strategy for Disseminated Langerhans Cell Histiocytosis. DAL HX-83 Study Group

Treatment of Langerhans cell histiocytosis (LCH) remains problematic. To test the hypothesis that rapid initiation and long-term continuation of chemotherapy can improve survival and reduce recurrence and late consequences of disseminated LCH, we have completed a prospective clinical trial (DAL HX-83). One hundred six newly diagnosed patients were stratified into three risk groups (A: multifocal bone disease [n = 28]; B: soft tissue involvement without organ dysfunction [n = 57]; C: organ dysfunction [n = 21]). All patients received an identical initial 6-week treatment (etoposide [VP-16], prednisone, and vinblastine), and continuation treatment for 1 year, slightly adapted according to stratification at diagnosis. It included oral 6-mercaptopurine and eight pulses of vinblastine and prednisone for all patients, plus VP-16 in group B and VP-16 and methotrexate in group C. Eighty-nine percent and 91% of patients in groups A and B and 67% of the most severely affected group C, achieved complete resolution of disease. The speed of resolution was rapid (median 4 months) and independent of disease severity. The frequency of recurrence after initial resolution was low (12%, 23%, and 42% in groups A, B and C); overall fully 77% of patients have remained free of recurrence. Permanent consequences developed after diagnosis in 20% of the patients. Diabetes insipidus after initiation of treatment occurred in only 10% of patients. Mortality (9%) was limited to patients of groups B (two patients) and C (eight patients). Finally, among the 106 patients treated by DAL HX-83 none have developed a malignancy (median follow-up 6 years, 9 months). The shorter duration of active disease, low rate of recurrence and permanent consequences, and improved survival among patients with poor prognosis support the strategy of rapid initiation of a predefined prolonged treatment upon the diagnosis of disseminated LCH.