Outcomes of children with newly diagnosed clear cell sarcoma of kidney following NWTS strategies in Shanghai China (2003–2021)

Background: Although clear cell sarcoma of kidney (CCSK) is rare, it is the second most common renal tumor in children after Wilms’ tumor. Here we aimed to evaluate the characteristics and outcomes of CCSK in China. Methods: : For this multicenter retrospective study, a total of 54 patients were enrolled from three children’s hospitals, between April 2003 and December 2021. Treatment comprised upfront radical nephrectomy, followed by radiotherapy and intensive chemotherapy. Clinical records were regularly updated. Prognostic factors and survival rates were evaluated. Results: : The 54 enrolled patients had a median age of 37 months (range, 4 months to 11.4 years). The stage distribution was 16% stage I (n=9), 30% stage II (n=16), 39% stage III (n=21), and 15% stage IV (n=8). After a median follow-up of 5.6 years, the 5-year event-free survival (EFS) was 82.4±5.4%, and overall survival was 88.1±4.6%. The EFS was 100% for stage I, 93.8 ±6.1% for stage II, 71.1±10.0% for stage III, and 68.6±18.6% for stage IV. Univariate analysis revealed that staging, tumor rupture, and inferior vena cava tumor thrombus were inferior prognostic factors. Among relapsed patients, relapse occurred a median of 11 months after diagnosis (range, 4–41 months), and 50% (4/8) achieved a second complete remission. Conclusions: : The outcomes of patients with stage I–III CCSK in China were comparable to findings in other developed countries. Better outcomes were achieved in stage IV CCSK by using an intensive chemotherapy regimen including carboplatin，which require confirmation by AREN0321. Treatment should be encouraged even in CCSK cases with metastasis and relapse. This clinical trial is registered with ChiCTR-PRCH-14004372.