Clinicopathological features and treatment of perivascular epithelioid cell tumor.

e23538 Background: Perivascular epithelioid cell tumor (PEComa) is a rare form of mesenchymal neoplasms. No clinical trial of large sample size regarding medical treatment of PEComa has been reported so far. Previous retrospective studies with small sample size have showed efficacy of mTOR inhibitors as treatment of PEComa. This study aimed to analyze the clinicopathological features of PEComa, and the efficacy of mTOR inhibitor in advanced PEComa. Methods: Medical information of patients diagnosed with PEComa and treated in Fudan University Shanghai Cancer Center were collected. Survival analysis was performed by Kaplan-Meier method. Radiological response was assessed according to RECIST version1.1. Results: A total of 17 patients were treated in our center during June 2007 to June 2020. PEComa mostly occurs in middle-aged women. The most common primary sites are pelvis, lung and abdomen. Relapse usually occurs within 2 years after radical surgery. Radical surgery is the main treatment for PEComa of limited stage, and remains the main option for those with limited recurrent lesions. Of the 13 patients with advanced malignant PEComa in our cohorts, the objective response rate of mTOR inhibitors in advanced malignant PEComa was 45.5%, and median progression-free survival was 27.7 months (95% CI 4.7-50.5 months). 2 patients discontinued mTOR inhibitor treatment due to pneumonitis combined with dyspnea and fever respectively. Conclusions: For advanced malignant PEComa, mTOR inhibitors are effective. Lung toxicity of mTOR inhibitor should be monitored.