Individualized prediction of recurrence-free survival after operation in patients with papillary renal cell carcinoma

Objective To explore the independent predictors for recurrence-free survival (RFS) in patients with papillary renal cell carcinoma (PRCC), and establish a nomogram to predict individual 2-year RFS. Methods The data of patients diagnosed in Xijing Hospital of the Air Force Medical University from June 2009 to May 2018 were retrospectively analyzed. A total of 71 patients with primary T1-4N0M0 unilateral tumor were included in this study. The median age was 54 (range from 25 to 83) years. There were 51 males and 20 females. There were 27 cases of typeⅠ, 44 cases of type Ⅱ, 36 cases of left tumor and 35 cases of right tumor. Patients with clinical Ⅰ, Ⅱ, Ⅲ, Ⅳ stage were 47 cases, 12 cases, 9 cases and 3 cases, respectively. Tumor necrosis occurred in 15 cases (21.1%). The average preoperative alkaline phosphatase (ALP) was 89.0(43.0-217.0) U/L, the average preoperative hemoglobin (Hb) was (132.5±19.9) g/L, with 20 cases (28.2%) of Hb<120 g/L before surgery; the average of preoperative Hb was (132.5±19.9) g/L, among which 20 cases (28.2%) had Hb<120 g/L before surgery; the average of preoperative neutrophils/lymphocytes (NLR) was 2.40 (1.03-6.77); radical nephrectomy was performed in 43 patients and nephrectomy was performed in 28 patients. The 1-, 2-, and 3-year RFS were calculated using Kaplan-Meier method and the differences among different subgroups were assessed using Log-rank test. Univariate and multivariate Cox regression analysis were used to identify the independent predictors for RFS, and the nomogram was developed using R software according to the results of multivariate Cox regression analysis. Furthermore, the predictive ability of the nomogram was internally validated using the Bootstrap method by calculating the C-index and drawing the calibration plot. Results After a median follow-up of 41 ( range from 25 to 83) months, 16 (22.5%) recurrence occurred, including 4 local recurrence and 12 distant recurrence, and 11 (68.8%) patients relapsed within 2 years after surgery. The 1, 2, and 3-year RFS were 88.6%, 80.4%, and 78.7%, respectively. Clinical stage Ⅱ (HR=3.655, 95%CI 1.036-12.890, P=0.044) and stage ≥Ⅲ(HR=3.654, 95%CI 1.008-13.248, P=0.049), preoperative ALP≥90U/L(HR=3.274, 95%CI 1.044-10.267, P=0.042), preoperative Hb<120 g/L (HR=4.771, 95%CI 1.553-14.660, P=0.006), and preoperative NLR≥2.40(HR=4.701, 95%CI 1.238-17.849, P=0.023) were identified as independent risk factors for RFS. On internal validation, the nomogram which integrates the four predictors of clinical stage, preoperative ALP, preoperative HB and preoperative NLR, has a good predictive performance (C-index =0.829, 95%CI 0.819-0.839). Conclusions In the present study based on single center data, clinical stage Ⅱ and ≥Ⅲ, preoperative ALP≥90 U/L, preoperative Hb<120 g/L and preoperative NLR ≥2.40 were independent predictors for postoperative RFS in patients with PRCC, and a new preoperative nomogram for predicting individual postoperative 2-year RFS was established, which would be helpful for urologists to develop more systematic treatment plans. Key words: Carcinoma, renal cell; Papillary; Recurrence; Nomogram