// Gang Song 1, * , Yu Fan 1, * , Gengyan Xiong 1 , Guangjie Ji 1 , Cong Huang 1 , Yongming Kang 1, 2 , Jinchao Chen 1 , Da Ren 1 , Qun He 1 , He Wang 1 , Gangzhi Shan 1 , Shuqing Li 1 , Zhisong He 1 and Liqun Zhou 1 1 Department of Urology, Peking University First Hospital, Institute of Urology, Peking University, National Urological Cancer Center, Beijing, China 2 Department of Urology, Suining Central Hospital, Sichuan, China * These authors contributed equally to this work Correspondence to: Gengyan Xiong, email: xgy13537221@163.com Liqun Zhou, email: zhoulqmail@sina.com Keywords: testicular tumor, malignant likelihood, predictive model, urological oncology Received: August 03, 2017 Accepted: November 19, 2017 Published: January 02, 2018 ABSTRACT Background: The clinical predictive factors for malignant testicular histology remain unclear because of the low prevalence. We initiated this study to predict the likelihood of malignant histology for testicular masses and decide more testis-sparing surgeries prior to surgery. Materials and Methods: 325 consecutive testicular mass patients who underwent radical orchiectomy or testicular preserving surgery (15/325) from January, 2001 to June, 2016 were enrolled in our study. We evaluated the predictive role of tumor diameter, cryptorchidism history, ultrasound findings, serum alpha fetoprotein (AFP) and human chorionic gonadotropin (HCG) levels to assess the likelihood of malignant testicular histology. A predictive nomogram was also generated to evaluate the quantitative probability. Results: There were 78 (24.0%) benign and 247 (76.0%) malignant testicular tumor patients in our study cohort. Larger tumor diameter (per centimeter increased, hazard ratio [HR] = 1.284, p = 0.036), lower ultrasound echo (HR = 3.191, p = 0.001), higher ultrasound blood flow (HR = 3.320, p < 0.001) and abnormal blood HCG (HR = 10.550, p < 0.001) were significant predictive factors for malignant disease in all testicular mass patients. In general, the nomogram was well calibrated for all predictions of malignant probability, and the accuracy of the model nomogram measured by Harrell's C statistic (c-index) was 0.92. The main limitation of the study was the retrospective design. Conclusions: According to our data, the proportion of patients who underwent radical orchiectomy for benign tumors (24%) was much larger than generally believed (10%). Our results suggest that the diameter, ultrasonic echo, ultrasonic blood flow and serum HCG levels could predict the malignancy in testicular mass patients.