Accuracy of multi-detector computed tomography (MDCT) in staging of renal cell carcinoma (RCC): analysis of risk factors for mis-staging and its impact on surgical intervention

Renal cell carcinoma T staging: Diagnostic accuracy of preoperative contrast-enhanced computed tomography

Renal cell carcinoma (RCC) accounts for 1-2% of all malignancies and is the most common renal tumor in adults. Imaging studies are used for diagnosis and staging. Tumor-Node-Metastasis staging strongly affects prognosis and management, while contrast-enhanced computed tomography (CECT) is regarded as a standard imaging technique for local and distant staging. The present study aimed to evaluate the accuracy of CECT for the preoperative staging of RCC by using surgical and pathological staging as the reference methods. This single-center prospective study was conducted between October 2019 and November 2021. The preoperative abdominal CT scans of patients suspected of having RCC were reviewed. Imaging data were collected, including tumor side and size, and perinephric fat invasion. Intraoperative notes were recorded, including the operation type, perinephric fat invasion, renal vein (RV) or inferior vena cava (IVC) tumor extension, and surrounding organ invasion. pathological data were collected on tumor size, RCC type, presence of clear margins, presence of renal capsule or perinephric fat invasion, renal sinus or pelvicalyceal system (PCS) invasion, segmental or main RV extension, and the involvement of Gerota's fascia and nearby organs. Preoperative CECT revealed that 42 out of 59 tumors had a greater maximum diameter than the pathological specimen, with an overall disparity of 0.25 cm. The specificity of CT for the detection of tumor invasion of the perinephric and renal sinus fat and PCS was 95%, and the sensitivity ranged from 80 to 88%. CT had an 83% sensitivity and a 95 specificity in detecting T4 stage cancer, with a 100% specificity for adrenal invasion. The concordance between radiographic and histological results for RV and IVC involvement was high, with specificities of 94 and 98%, and sensitivities of 80 and 100%, respectively. Overall accuracy for correct T staging was 80%. In conclusion, CECT is accurate in the local T staging of RCC, with high sensitivity and specificity for estimating tumor size and detecting extension to nearby structures and venous invasion.

Predictive features of pre-operative computed tomography and magnetic resonance imaging for advanced disease in renal cell carcinoma

OBJECTIVE

We evaluated predictive features of pre-operative computed tomography and magnetic resonance imaging for advanced disease in renal cell carcinoma.

MATERIALS AND METHODS

92 patients with pathologically confirmed diagnosis of renal cell carcinoma were included in our study. Patients were divided into two groups according to preoperative imaging as computed tomography (CT) (55 patients) and magnetic resonance imaging (MRI) (37 patients). Within the imaging groups, the patients were divided into two groups according to pathological tumor stage: 1-2 (pT1-2) versus ≥ pT3a. It was evaluated whether there was a difference between the two groups in terms of the presence of pre-operative imaging (CT and MRI) features. Predictive value of these features for ≥ pT3a disease was evaluated both for CT and MRI.

RESULTS

The cut-off value for the Gerota's fascia thickness in predicting ≥ pT3a disease was calculated as 0.205 cm. Positive predictive value (PPV) for Gerota's fascia thickness was 52.4% (31.0-73.7) and 66.7% (40.0-93.3) for CT and MRI respectively. The PPV value for renal capsule invasion was 75.0% (53.8-96.2) and 90.0% (71.4-108.6) for CT and MRI respectively. PPV of perirenal fat invasion for CT and MRI was 69.2% (44.1-94.3) and 81.8% (59.0-104.6) respectively.

CONCLUSION

Renal capsular invasion and perirenal fat invasion are reliable signs for locally advanced (≥ pT3a) renal cell carcinoma both in CT and MRI. Gerota's fascia thickness has relatively low PPV value for prediction of locally advanced disease. Presence of enlarged collateral vessels, tumor necrosis, perinephric stranding are not reliable signs. For all predictors MRI seems more reliable than CT.

Preoperative Assessment of Renal Sinus Invasion by Renal Cell Carcinoma according to Tumor Complexity and Imaging Features in Patients Undergoing Radical Nephrectomy

Objective

To identify the association between renal tumor complexity and pathologic renal sinus invasion (RSI) and evaluate the usefulness of computed tomography tumor features for predicting RSI in patients with renal cell carcinoma (RCC).

Materials and Methods

This retrospective study included 276 consecutive patients who underwent radical nephrectomy for RCC with a size of ≤ 7 cm between January 2014 and October 2017. Tumor complexity and anatomical renal sinus involvement were evaluated using two standardized scoring systems: the radius (R), exophytic or endophytic (E), nearness to collecting system or sinus (N), anterior or posterior (A), and location relative to polar lines (RENAL) nephrometry and preoperative aspects and dimensions used for anatomical classification (PADUA) system. CT-based tumor features, including shape, enhancement pattern, margin at the interface of the renal sinus (smooth vs. non-smooth), and finger-like projection of the mass, were also assessed by two independent radiologists. Univariable and multivariable logistic regression analyses were performed to identify significant predictors of RSI. The positive predictive value, negative predictive value (NPV), accuracy of anatomical renal sinus involvement, and tumor features were evaluated.

Results

Eighty-one of 276 patients (29.3%) demonstrated RSI. Among highly complex tumors (RENAL or PADUA score ≥ 10), the frequencies of RSI were 42.4% (39/92) and 38.0% (71/187) using RENAL and PADUA scores, respectively. Multivariable analysis showed that a non-smooth margin and the presence of a finger-like projection were significant predictors of RSI. Anatomical renal sinus involvement showed high NPVs (91.7% and 95.2%) but low accuracy (40.2% and 43.1%) for RSI, whereas the presence of a non-smooth margin or finger-like projection demonstrated comparably high NPVs (90.0% and 91.3% for both readers) and improved accuracy (67.0% and 73.9%, respectively).

Conclusion

A non-smooth margin or the presence of a finger-like projection can be used as a preoperative CT-based tumor feature for predicting RSI in patients with RCC.

Update on the Role of Imaging in Clinical Staging and Restaging of Renal Cell Carcinoma Based on the AJCC 8th Edition, From the AJR Special Series on Cancer Staging

This article reviews the essential role of imaging in clinical staging and restaging of renal cell carcinoma (RCC). To completely characterize and stage an indeterminate renal mass, renal CT or MRI without and with IV contrast administration is recommended. The critical items for initial clinical staging of an indeterminate renal mass or of a known RCC according to the TNM staging system are tumor size, renal sinus fat invasion, urinary collecting system invasion, perinephric fat invasion, venous invasion, adrenal gland invasion, invasion of the perirenal (Gerota) fascia, invasion into other adjacent organs, the presence of enlarged or pathologic regional (retroperitoneal) lymph nodes, and the presence of distant metastatic disease. Larger tumor size is associated with higher stage disease and invasiveness, lymph node spread, and distant metastatic disease. Imaging practice guidelines for clinical staging of RCC, as well as the role of renal mass biopsy, are highlighted. Specific findings associated with response of advanced cancer to antiangiogenic therapy and immunotherapy are discussed, as well as limitations of changes in tumor size after targeted therapy. The accurate clinical staging and restaging of RCC using renal CT or MRI provides important prognostic information and helps guide the optimal management of patients with RCC.