The goal of this clinical trial is to investigate whether robot-assisted laparoscopic partial nephrectomy by extraperitoneal approach in the prone position had any advantages over the traditional lateral position. The main questions it aims to answer are:

Is prone surgery safe and feasible, and what are the advantages over the traditional lateral position? Does surgery in the prone position have an impact on the patients' prognosis? Researchers will compare prone position to lateral position to see if robot-assisted laparoscopic partial nephrectomy by extraperitoneal approach in the prone position has any advantages over the traditional lateral position and whether it has any significant effect on the prognosis of the patients.

Participants will be randomly allocated 1:1 to two groups: prone position group and lateral position group. The enrolled patients will be underwent robotic-assisted laparoscopic partial nephrectomy via extraperitoneal approach according to the corresponding positions of their groups. Demographic indicators and perioperative-related indicators will be counted and recorded. CT or MRI and related biochemical examinations will be reviewed at 1 month, 3 months, 6 months and 1 year after surgery, and every 1 year thereafter. The similarities and differences of the indicators in different positions will be analysed, and subgroup analyses will be performed according to the corresponding results.

Inclusion Criteria:

1. . Patients with preoperative imaging suggestive of renal occupancy;
2. . Sex is not limited;
3. . Age ≥18 years;
4. . Clinical staging consistent with indications for partial nephrectomy;
5. . Suitable for robotic-assisted laparoscopic partial nephrectomy via extraperitoneal approach as judged by relevant preoperative clinical data;
6. . Agree to provide basic clinical information and pathological and imaging data for scientific research and sign an informed consent form;
7. . Agree to provide monitoring results during the follow-up recurrence monitoring process.

Exclusion Criteria:

1. . Patients who did not meet the indications for partial nephrectomy and did not undergo robotic-assisted laparoscopic partial nephrectomy via extraperitoneal approach;
2. . Patients who refuse to undergo or cannot tolerate surgery in the appropriate position;
3. . Patients with incomplete documentation of relevant data to provide accurate demographic, perioperative, and prognostic data;
4. . Any condition which, in the opinion of the investigator, may be detrimental to the subject or result in the inability of the subject to meet or perform the requirements of the study;
5. . Patients who are unable to provide written informed consent;