OBJECTIVE: To evaluate the feasibility and application value of mixed reality technology (MR) in Primary retroperitoneal tumour (PRT) surgery.
METHODS: From 276 patients who underwent PRT resection at the First Affiliated Hospital of Xi\'an Jiaotong University, we screened 46 patients who underwent MR-assisted retroperitoneal tumour resection and 46 patients who underwent tumour resection without MR assistance. The intraoperative and postoperative recovery of the patients in both groups were compared, and the reliability and validity of the application of MR were further examined using the Likert scale.
RESULTS: There was a significant difference in the mean intraoperative bleeding volume between the two groups, but it was reduced in the MR group. The results of the Likert scale showed higher scores in the MR group than non-MR group.
CONCLUSIONS: MR can be used to assist PRT resection and has great potential to improve the rate of complete retroperitoneal tumour resection.

BACKGROUND: Primary retroperitoneal tumours (PRTs) are rare soft tissue tumours originating from the retroperitoneum. Although there has been considerable progress recently in diagnosis and treatment, the overall survival rate has not improved qualitatively. This study aimed to explore the clinical features, therapeutic strategies and prognosis of PRTs.
METHODS: Retrospective analysis of clinical data for 121 PRT patients admitted to Peking University Shenzhen Hospital from April 2003 to February 2017.
RESULTS: A total of 113 patients underwent surgery and 8 chose nonsurgical palliative treatment. There were 53 males and 68 females (ratio, 1:1.3; average age, 40.75 years), and the average tumour diameter was 9.69(2-40)cm. A total of 104 patients (92.04%) underwent complete resection, 5 (4.42%) underwent palliative resection and 21 (18.58%) underwent combined visceral resection. The pathological diagnosis was benign in 88 cases (72.73%) and malignant in 33 cases (27.27%). A total of 101 patients (83.47%) were followed for an average of 5.82 years. At the end of follow up, the recurrence and survival rates were 2.63% and 93.42% for benign tumours, respectively, and 24.00% and 60.00% for malignant tumours (p<0.01).
CONCLUSIONS: Imaging plays important roles in localising and characterising tumours, guiding treatment strategies. Complete tumour resection is key to reducing postoperative recurrence and improving survival. According to the postsurgical pathological results, combinations including radiotherapy, chemotherapy or targeted therapy are beneficial for improving prognosis.

INTRODUCTION Benign and malignant primary retroperitoneal tumours (PRT) have different clinical manifestations and pathological characteristics. We explore the characteristics and evaluate the value of computed tomography (CT) for PRT. METHODS Fifty-six benign and fifty-seven malignant PRT with clinical, radiographic and surgical data were retrospectively investigated. Statistical analysis was carried out using SPSS software. RESULTS We found that mean size of benign tumours was 12.4 ± 7.7cm but 20.7 ± 11.6cm in malignant cases (P < 0.05). The accuracy of CT localisation was approximately 70%. The sensitivity and specificity of CT diagnosis for benign tumours were 96% and 85%, respectively; 51 (91%) underwent complete resection among benign cases but 42 (74%) in malignant cases (P < 0.05). Sensitivity of CT evaluation for invaded organs and vessels was 50% and 65%, respectively, and specificity was 88% and 81%, respectively. CONCLUSIONS Large size, no capsule, irregular margin, heterogeneous density and specific enhancement pattern on CT are highly suggestive of malignancy. CT is the most useful tool in assessing the size and characteristics of PRT but it does not have the sensitivity to assess the involvement of organs and vessels.