Cancer - Kidney(구연) (E-074) Prognostic Factors for Overall Survival in Patients with Clear Cell Metastatic Renal Cell Carcinoma: Model Design and External Validation with Previous Models 1College of Medicine, Korea University, 2Department of Urology, Korea University Ansan Hospital, 3Department of Urology, National Cancer Center, Goyang, Republic of Korea, 4Department of Urology, Sungkyunkwan University College of Medicine, Seoul, Republic of Korea, 5Department of Urology, Seoul National University College of Medicine, Seoul, Republic of Korea, 6Department of Urology, University of Ulsan College of Medicine, Seoul, Republic of Korea, 7Department of Urology, Medical School, Chonnam National University, Hwasun‐gun, Republic of Korea, 8Department of Urology, Seoul National University Bundang Hospital, Seongnam, Republic of Korea, 9Department of Urology, Seoul St. Mary's Hospital, The Catholic University, Seoul, Republic of Korea Dong Ryul Shin1, Jae Young Park1,2, Sung Han Kim3, Minyong Kang4, Seong Il Seo4, Cheol Kwak5, Chang Wook Jeong5, Cheryn Song6, Eu Chang Hwang7, Jung Kwon Kim8, Hakmin Lee8, Sung‐Hoo Hong9, Jinsoo Chung3 on behalf of Korean Renal Cancer Study Group OBJECTIVES To design a new prognostic model for the overall survival of clear cell metastatic renal cell carcinoma (mRCC) patients and externally validate it to two most renowned previous models: the International Metastatic Renal Cell Carcinoma Database Consortium model (IMDC), and the Memorial Sloan Kettering Cancer Center (MSKCC) model. MATERIALS & METHODS Data of 790 patients previously diagnosed with mRCC and receiving targeted therapy as their first-line treatment were pooled to this study. Four hospitals (n = 619) were used to design the new model and other 5 hospitals (n = 171) were used for external validation (Ext cohort). After detecting prognostic factors in multivariable Cox proportional-hazards regression, patients were classified into three risk groups, Favorable (0), Intermediate (1–2), and Poor (3 and over), by the number of prognostic factors, and we designated this grouping model KRoCS. In the external validation procedure, we compared three models— KRoCS, IMDC, MSKCC—with the Ext cohort. Statistical parameters including Akaike information criterion (AIC), concordance index and generalized R2 were calculated to compare model’s fitness with the Ext cohort. RESULTS Seven variables—more than two metastasis sites, no prior nephrectomy, ECOG(Eastern Cooperative oncology Group) performance status ≥ 2, low hemoglobin (M < 13 g/dL, F < 11.5 g/dL), high serum corrected calcium (> 10.2 mg/dL), high serum neutrophil (> 7000/μL), high serum alkaline phosphatase(ALP) (> 88 U/L)—were identified as prognostic factors for poor OS. Also, risk groups were categorized into three groups: Favorable (n = 102, 61.1 mo), Intermediate (n = 362, 26.5 mo), Poor (n = 155, 6.72 mo). KRoCS ranked the first in all three statistical parameters, AIC, concordance index and generalized R2, and MSKCC and IMDC followed in sequence with marginal difference. In Chi-squared test, KRoCS exhibited no significant difference in patient discrimination in both cohorts while IMDC and MSKCC revealed significant difference (P < 0.05) with KRoCS. CONCLUSION The new KRoCS model was non-inferior to previous models. The new model KRoCS may provide useful information for counselling clear cell mRCC patients with life-expectancy. keywords : renal cell carcinoma, prognosis, survival