Radiological Correlates of pT3a Kidney Cancer: Importance of Irregular Tumor Sinus Border

Purpose: Preoperative assessment of T3a renal-cell-carcinoma (RCC) in absence of main renal vein involvement or lymph node enlargement is challenging but has potential implications for counseling and prognosis. Materials and Methods: A retrospective review of 1129 cT1-T3aN0M0 RCC patients managed with partial/radical nephrectomy (PN/RN) in our institution (2012-2014) was performed. Exclusion criteria included radiological evidence of main renal vein involvement or substantial lymphadenopathy. Eleven radiological findings suggestive of aggressive tumor biology or invasive phenotype based on prior literature were assessed for correlation with pT3a status. These included perinephric-findings (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]), and tumor-necrosis, infiltrative-features, and tumor-size. Radiological assessment was blinded to final pathology. Sensitivity/specificity and logistic-regression analyses assessed the performance of each imaging-finding for detecting pT3a tumors. Results: Median tumor-size was 4.0cm and R.E.N.A.L. was 8. Median follow-up was 53 months (IQR:28-64). pT3a tumors were found in 281 patients (25%) and strongly correlated with local and systemic recurrence (p<0.02). 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 included ITSB(yes/no) and tumor-size as a continuous variable (C-index=0.84). Addition of other imaging-findings 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 for assessment of ITSB were 0.89/0.98, respectively. Conclusions: Our data suggest that ITSB and tumor-size associate with pT3a RCC, which could impact patient counseling.