Multiple bone lesions (single-system multifocal bone lesions)

Chemotherapy. The most commonly used systemic chemotherapy regimen is the combination of vinblastine and prednisone. Based on the results of the HISTSOC-LCH-III (NCT00276757) trial, 12 months of treatment with weekly vinblastine (6 mg/m2) for 7 weeks, then every 3 weeks, is used for good responders.[29] Prednisone (40 mg/m2) is given daily for 4 weeks, then tapered over 2 weeks. Afterward, prednisone is given for 5 days at 40 mg/m2 every 3 weeks with the vinblastine injections. A short treatment course (<6 months) with only a single agent (e.g., prednisone) is not sufficient, and the number of relapses is higher. A reactivation rate of 18% was reported with a multidrug treatment regimen that was used for 6 months versus a historical reactivation rate of 50% to 80% with surgery alone or with a single-drug treatment regimen.[106] A comparison of results from two trials in Japan revealed no improvement in progression-free survival rates (66% vs. 65%) when additional prednisone and a prolonged maintenance phase were added.[107]