Outcome after Radiotherapy for Langerhans Cell Histiocytosis Is Dependent on Site of Involvement

Publication date: Available online 6 November 2017
Source:International Journal of Radiation Oncology*Biology*Physics
Author(s): James Laird, Jennifer Ma, Karen Chau, Monica Chelius, Weiji Shi, Zhigang Zhang, Benjamin H. Lok, Joachim Yahalom
PurposeLangerhans cell histiocytosis (LCH) is a rare malignant disease characterized by histiocytic proliferation. We intended to characterize the efficacy and safety of radiation therapy (RT) in a contemporary cohort and to explore if there are sites at higher risk for local recurrence.Materials/MethodsBetween 1995 and 2015, we identified 39 consecutive LCH patients who were treated primarily with radiation therapy. Patients were staged by single/multisystem involvement (SS/MS) and established risk organ criteria. In 46 irradiated lesions, clinical and radiologic responses were evaluated at multiple time points after radiotherapy. Patient demographics, treatment, and local failure were compared by site of lesion.ResultsMedian age at RT was 35 years (range 1.5 – 67). Twelve patients had multisystem involvement, and of those, 5 patients had disease in organs considered to be high-risk. The following sites were irradiated: bone (31), brain (6), skin (3), lymph node (3), thyroid (2), and nasopharynx (1). Median dose was 11.4 Gy (7.5 – 50.4). At a median follow-up of 45 months (6 – 199), local recurrence or progression was noted in 5 of 46 (11%) lesions. There were no local failures of the 31 bone lesions evaluated, while the 3-year freedom from local failure in the 15 non-bone lesions was 63% (95% CI 32 – 83%; p = 0.0008). Local failures occurred in 2 of 3 skin lesions, in 2 of 6 brain lesions, and 1 of 3 lymph node lesions. Deaths were recorded in 5 of 39 (13%) patients, all of whom were adults with multisystem disease.ConclusionRadiotherapy is a safe and effective measure for providing local control of LCH involving the bone. While bone lesions are well controlled with low doses of radiation, disease in other tissues such as the skin and brain may require higher doses of radiation or additional treatment modalities.

Teaser

Langerhans cell histiocytosis is a rare histiocytic malignancy associated with a wide range of clinical presentations and outcomes. We explored treatment patterns and outcomes in a cohort of 39 patients with 46 radiation-treated lesions. We found the rate of local failure was significantly higher in patients with non-bone lesions, especially of the skin and brain, compared to excellent local control in bone lesions with relatively low doses of radiation.


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