Risk of leptomeningeal metastasis in children with parameningeal rhabdomyosarcoma with intracranial spread

Abstract

   Introduction. Soft tissue tumors account for up to 8 % of all malignant neoplasms in children. According to the international histological classification, about 150 different morphological variants of soft tissue tumors have been registered, of which 45 % are rhabdomyosarcoma (RMS). Most often, RMS occurs in early childhood – the average age of patients at the time of diagnosis is 5 years. The incidence rate of RMS is 0.9 per 100,000 children. In 25 % cases, the initial diagnosis reveals distant metastasis to the lungs, bones, bone marrow, and 8 % – leptomeningeal metastasis. More than 7 % of patients with localized parameningeal RMS develop leptomeningeal metastasis, according to the Rhabdomyosarcoma Study Group.   Purpose of the study – report the incidence, prognosis of leptomeningeal metastasis and treatment outcomes in children with intracranial spread of RMS.   Materials and methods. The study included 45 patients aged 1 to 17 years with a diagnosis of RMS of parameningeal localization with intracranial spread, who received special treatment from 2003 to 2020. The study included 6 (20 %) patients in whom the tumor developed in early childhood (up to 3 years). The boys predominated – 25 (55.5 %) in the study. The primary tumor spread to the orbit in 7 (15 %) cases, the skull base in 7 (15 %) cases, the middle ear in 4 (8 %) cases, the nasopharynx in 3 (6 %) cases, and the brain substance was affected in 16 (35 %). Metastases in regional lymph nodes were determined in 7 (15 %) patients. Multiple metastatic lesions of bones and bone marrow – 4 (9 %) cases, leptomeningeal metastases – in 2 (4 %). 45 (100 %) patients received drug treatment according to the protocols approved by the Academic Council of the Research Institute of Pediatric Oncology and Hematology at N. N. Blokhin National Medical Research Centerof Oncology, Ministry of Health of Russia. Radiation therapy was performed in 33 (74 %) patients, while total focal dose of 50 Gy was administered to the primary tumor. Affected lymph nodes of the neck were irradiated in 10 (23 %) patients, total focal dose is 45.0 Gy. Surgical treatment was performed in 15 (34 %) patients. Multicomponent treatment was performed in 15 (34 %) patients.   Results. During the observation period from 12 months to 14 years, 21 (49 %) patients are alive. 21 (51 %) patients died from tumor progression, 1 (2 %) died from complications of special treatment.   Conclusions. The treatment of this group of patients is one of the urgent problems of pediatric oncology, which is based on polychemotherapy, supplemented by intrathecal administration of anticancer drugs and craniospinal irradiation. The development of new therapies requires a multidisciplinary approach to achieve a significant improvement in the survival of children with leptomeningeal metastases RMS of parameningeal localization.