Treatment of low-risk disease: single-system or multisystem LCH

Over many years, national and international study groups have defined risk-based therapy groups for allocation of LCH patients on the basis of mortality risk and risk of late effects of the disease.

Depending on the site and extent of disease, treatment of LCH may include observation (after biopsy or curettage), surgery, radiation therapy, or oral, topical, and intravenous medication. The recommended duration of therapy is 12 months for patients who require chemotherapy for single-system bone, skin, or lymph node involvement.

For patients with high-risk and low-risk multisystem disease, the reactivation rate after 6 months of therapy was as high as 50% on the HISTSOC-LCH-I and HISTSOC-LCH-II trials.[28,84] The German-Austrian-Dutch (Deutsche Arbeitsgemeinschaft für Leukämieforschung und Behandlung im Kindesalter [DAL]) group trials treated patients for 1 year and had fewer relapses (29%).[76,85] On the basis of these findings, the HISTSOC-LCH-III trial was designed to administer 12 months of chemotherapy for all high-risk multisystem patients and to randomly assign low-risk multisystem patients to either 6 months or 12 months of therapy. In patients with low-risk or high-risk disease who received 12 months of therapy, the reactivation rate was significantly reduced to approximately 30%.[29]

The standard treatment for LCH is based on data from international trials with large numbers of patients. However, some patients may have LCH involving only the skin, mouth, pituitary gland, or other sites not studied in these international trials. In these cases, therapy recommendations are based on case series that lack the evidence-based strength of the trials.

Clinical trials organized by the Histiocyte Society have been accruing patients on childhood treatment studies since the 1980s. Information about centers enrolling patients on these trials can be found on the ClinicalTrials.gov website.

Treatment options for patients with low-risk, single-system or multisystem disease depend on the site of involvement, as follows: