1908. pT3a Kidney Cancer: Importance of Irregular Tumor Sinus Border
Authors * Denotes Presenting Author
  1. Alain Rizk *; Cleveland Clinic
  2. Yun-Lin Ye; Cleveland Clinic
  3. Diego Aguilar Palacios; Cleveland Clinic
  4. Steven Campbell; Cleveland Clinic
  5. Erick Remer; Cleveland Clinic
Preoperative detection of T3a renal cell carcinoma (RCC) in the absence of evident renal vein involvement is challenging. We hypothesize that the presence of irregular tumor sinus border (ITSB) can predict pathological T3a status and a higher cancer recurrence rate among patients who undergo nephrectomy.

Materials and Methods:
We performed a retrospective review of all cT1-T3, N0, M0 RCC patients managed with partial or radical nephrectomy at our institution from 2012-2014. 1129 patients without radiological evidence of main renal vein involvement or lymphadenopathy >1.5cm were included. All images were blindly reviewed to assess for inter/intra observer variability. Tumors extending to renal sinus and demonstrating irregular tumor sinus border (ITSB) were considered positive. Ten other finding potentially associated with T3a were also reviewed. Sensitivity/logistic regression analyses assessed the performance of ITSB in detecting pT3a tumors, and survival-analyses assessed tumor recurrence.

Median tumor-size was 4.0 cm and median follow-up was 53 months (IQR:28-64 months). pT3a tumors were found in 281 patients (25%) and strongly correlated with increased risk of local and systemic recurrence (p<0.02). Eleven factors were assessed for possible correlation with pT3a status, including perinephric-features (stranding, enhancing-nodule, collateral-vessels, or irregular-perinephric-tumor-contour), findings within the sinus [stranding, collecting-system invasion, branch-vein enlargement, or irregular-tumor-sinus-border (ITSB)], tumor-necrosis, infiltrative-features, and tumor-size. ITSB was found in 350 patients (31%) and was the strongest predictor of pT3a status. Sensitivity/specificity/PPV/NPV/OR/C-Index for ITSB were 75%/84%/61%/91%/15.8(11.4-21.9)/0.80, for correlation with pT3a, respectively. The best predictive model for pT3a included ITSB and tumor-size as a continuous variable (C-index=0.84). Addition of other imaging-features did not improve the model (C-index=0.84). ITSB was the strongest contributor in all multivariable-models and also strongly correlated with recurrence-free-survival. Inter/intra-observer correlations were 0.89/0.98, respectively.

ITSB and tumor size can predict pT3a RCC preoperatively which could impact patient counseling and management. Further studies and external validation is required.