Clinical characteristics and prognosis of childhood rhabdomyosarcoma: a ten-year retrospective multicenter study.

PURPOSE: Rhabdomyosarcoma (RMS) is the most frequent soft tissue sarcoma in children. We have retrospectively explored the treatment results of childhood RMS and identified prognostic factors in multicenter in China, in order to lay the foundation for further multicenter study.

METHODS: This retrospective study was carried out analyzing the medical records of 161 patients with the pathological diagnosis of RMS from January, 2001 to February, 2014 at 5 large cancer centers in China. The data was reviewed clinico-epidemiological factors. Age, gender, histology type, primary site, tumor size, intergroup rhabdomyosarcoma study (IRS) group and results of treatments were evaluated. Patients were followed up to Dec 31, 2014.

RESULTS: The median age of our patients was 51 months. 10.5% of our patients were infants. The genitourinary system was the most common primary site of tumor (43.5%). The proportion of primary site of head and neck except parameningeal, at 28.2% (42 cases), while the proportion of parameningeal region was 4.6% (7 cases). The histological findings were as follows: 130 cases (80.7%) with embryonal, 19 cases (11.9%) with alveolar and 5 cases (3.1%) with botryoid type. According to the classification system of the IRS group, 1 case (0.6%) was group I, 54 cases (33.5%) were group II, 46 cases (28.6%) were group III and 60 cases (37.3 %) were group IV. 149 patients were treated and followed-up regularly, Patients in Beijing children's hospital (n=95) were enrolled in IRS-II/COG-D9803, D9802 protocols. while the other patients (n=54) started on treatment according to Chinese Anti-cancer Association protocol. There were median time of 51 months for following up, 60 occurred event. The ten-year event free survival rate was 53.4±5.1%, overall survival was 65.3±6.3%. The relations between outcome and age (0.046), primary site (0.022), pathologic subtype (0.013), tumor size (0.008) and IRS group (P=0.000) were associated significantly with event free survival. Among the variables, age (P=0.028) and IRS group (P=0.000) were associated significantly with overall survival. Multivariate analysis showed that overall survival for RMS was dependent on IRS group (P=0.026).

CONCLUSIONS: The epidemiological characteristics of our patients are quite similarly to the worldwide data. Except for the higher prevalence of group IV in our patients and the higher percentage of patients with primary tumor site in the genitourinary system, this study showed that overall survival for RMS is depended on disease group.