[Clinical analysis of 21 children with Xp11.2 translocation renal cell carcinoma]

Objective: To summary the clinical characteristics, treatment and prognosis of children with Xp11.2 translocation renal cell carcinoma. Methods: In this case-series study, clinical data including sex, age, clinical manifestations, staging, treatment modalities, and follow-up outcomes of 21 children with Xp11.2 translocation renal cell carcinoma who first visit and received treatment and follow-up at the First Affiliated Hospital of Zhengzhou University from June 2019 to June 2025 were collected. The Kaplan-Meier method was used for survival analysis, and the Log-rank test was applied for univariate prognostic analysis. Results: Among the 21 children, 12 were males, 9 were females. The age at diagnosis was 15 (12, 16) years. Gross hematuria and flank pain were the main frequent symptoms, which occurred on 10 and 5 children respectively. According to the American Joint Committee on Cancer (AJCC) staging system, there were 7 children of stage Ⅰ, 2 children of stage Ⅱ, 9 children of stage Ⅲ, 3 children of stage Ⅳ. Children with stage Ⅰ-Ⅱ received surgical treatment only. With follow-up time of 19 (8, 52) months, none experienced disease recurrence. The 3-year event-free survival (EFS) and overall survival (OS) rates were both 100%. Among 9 children with stage Ⅲ, 4 received surgery alone, 2 of whom experienced recurrence; 5 received surgery plus tyrosine kinase inhibitor (TKI), 1 of whom developed recurrence. Among 3 children of stage Ⅳ, 1 had extensive metastasis and was treated with sunitinib only, subsequently progressed and died; 1 received surgery plus sunitinib and later developed disease progression; 1 achieved partial remission after surgery combined with programmed death-1 (PD-1) inhibitors and axitinib therapy. The progression or recurrence time was 7.0(6.5, 9.5) months. Among the 5 relapsed or progressive children, 1 child died; 4 children were treated with PD-1 inhibitor combined with axitinib, with 3 achieving complete remission and 1 obtaining stable disease. The follow-up duration for stage Ⅲ-Ⅳ children was 30.0 (12.8, 44.5) months, and the 3-year EFS and OS rates were 55% (95%CI 23%-78%) and 91% (95%CI 49%-97%), respectively. The follow-up duration for all 21 children was 28 (11, 44) months, with 3-year EFS and OS rates of 73% (95%CI 38%-91%) and 94% (95%CI 67%-99%), respectively. AJCC stage Ⅲ-Ⅳ and the presence of regional lymph node metastasis were both associated with disease progression and recurrence (both P<0.05). Conclusions: Children of Xp11.2 tRCC predominantly presents primarily with gross hematuria. Children with stage Ⅰ-Ⅱ can be treated with surgery alone, while those with stage Ⅲ-Ⅳ can receive surgical resection combined with tyrosine kinase inhibitor therapy. The overall prognosis is favorable. AJCC stage Ⅲ-Ⅳ and the presence of regional lymph node metastasis are poor prognostic factors. PD-1 inhibitor combined with axitinib therapy can be used for the treatment of children with metastatic, recurrent or progressive disease.