This clinical trial aims to compare the effectiveness and safety of two treatment options for patients with high-risk upper tract urothelial carcinoma (UTUC). One group will receive neoadjuvant chemotherapy with gemcitabine and cisplatin followed by surgery (radical nephroureterectomy), while the other group will undergo surgery without chemotherapy. The primary goal is to assess the pathological response to treatment, focusing on how much the tumor shrinks before surgery. The trial will also evaluate the safety of the treatments, overall survival, and recurrence-free survival. This study will help determine whether adding chemotherapy before surgery improves outcomes for patients with high-risk UTUC.

Inclusion Criteria:

1. Histologically confirmed high-risk upper tract urothelial carcinoma (UTUC).
2. Clinically non-metastatic UTUC (N≤1, M0) based on imaging (CT/MRI).
3. Planned for radical nephroureterectomy (RNU).
4. ECOG performance status of 0 or 1.
5. Sufficient renal function (GFR ≥45 mL/min) and able to tolerate chemotherapy with cisplatin.
6. Age ≥18 years.
7. Informed consent signed.

Exclusion Criteria:

1. Imaging shows ≥N2 disease or metastatic disease (M1).
2. History of invasive or lymph node-positive UTUC or invasive disease in the contralateral upper tract in the last 2 years.
3. Single kidney or contraindication to cisplatin.
4. Currently participating in other interventional clinical trials.
5. History of non-urothelial malignancies (except treated skin basal cell carcinoma or cervical carcinoma in situ).
6. Pregnant or breastfeeding women.
7. Any other medical condition deemed inappropriate by the treating physician.

1. Data Privacy and Ethical Considerations: Due to the sensitive nature of the IPD, which contains private health information, sharing of this data may pose privacy risks and violate regulations such as GDPR or HIPAA. The study's ethical approval also restricts public access to IPD to safeguard patient confidentiality.
2. Data Security: To ensure the protection of patient information and prevent potential data breaches, access to the IPD will be strictly limited to the internal research team.
3. Lack of Data Sharing Agreement: While we support data sharing, a formal agreement with external researchers or public repositories has not been established for this study at present.
4. Group-level Analysis: The primary analyses of this study are based on aggregated group data rather than individual patient-level data. As such, sharing IPD does not significantly impact the reproducibility or verification of the study's results.