Pediatric non-rhabdomyosarcoma soft tissue sarcomas: multimodality approach results and validation of American Children's Oncology Group risk stratifications——a study of single-institutional series

Abstract

Objective To investigate the clinical characteristics, survival, factors of prognosis and therapeutical strategy of pediatric non-rhabdomyosarcoma soft tissue sarcomas(NRSTS). Methods There were 34 cases of NRSTS treated in Department of Orthopaedic Oncology, Peking University Cancer Hospital during July 2007 and March 2015.The clinical and pathological data and outcome of multimodality approach were retrospectively studied, the survival analysis was performed. Results There were 21 male and 13 female cases, and the median age was 14 years, ranging from 7 to 18 years old.Mean and median size was 5.0 cm and 3.0 cm, ranged 0.5-22.0 cm.Synovial sarcoma was the most common type among the 9 sorts of histologies[29.4%(10/34 cases)], and limb was the most common site [67.6%(23/34 cases), accounting for 50.0% (17/34 cases)by lower limb]. There were 28 cases, 2 cases, 2 cases, 2 cases in Intergroup Rhabdomyosarcoma Study (IRG) groupⅠ, Ⅱ, Ⅲ, Ⅳ, respectively, and 23 cases, 7 cases, 4 cases in Children's Oncology Group (COG) low, moderate and high risk group respectively.The median follow-up was 35 months, ranging from 6 to 96 months.There were 2 cases of local recurrence, 1 case of distant recurrence, 2 cases of metastases of lymph node and distant sites, and 1 case of local and distant recurrence.The 2-year overall survival rate was 89.2%, 100.0%, 70.0% for total group, COG low risk group, COG moderate and high risk group, respectively.For 28 cases of tumors without any nodular or distant metastasis, the 2-year local recurrence-free survival and distant recurrence-free survival rate was 96.4% and 87.6% respectively.IRS group, COG risk group and size of tumor were associated with the prognosis.The groups of completely resected tumor(P=0.007), COG low risk (P=0.014)and tumors no larger than 5.0 cm in diameter(P=0.037) had more favorable overall survivals.There were 14 cases, 10 cases, 4 cases, 2 cases, 2 cases, 2 cases who had surgery alone, surgery plus chemotherapy, surgery plus chemoradiotherapy, surgery plus radiation, chemoradiotherapy alone and chemotherapy alone, respectively, as multimodality approaches.Mesna+ Adriamycin+ Ifosfamide regimen(Pirarubicin 40 mg/m2, Ifosfamide 10 g/m2) was the main(17/18 cases) choice as chemotherapy, with a total and mean cycles of chemotherapy for every case of 2-12 and 4.6 respectively. Conclusions This series of NRSTS showed favorable oncological outcomes after a multimodality approach composed of surgery, radiation and chemotherapy on MAI regimen.The COG risk stratifications were firstly adopted in domestic study of pediatric NRSTS, with prognostic efficacy being validated.Risk-based multimodality approach was also recommended. Key words: Non-rhabdomyosarcoma soft tissue sarcomas; Survival analysis; Risk stratifications; Multimodality approach