Pathologic Upstaging after Laparoscopic Radical Nephrectomy

ACR Appropriateness Criteria® Staging of Renal Cell Carcinoma: 2022 Update

Renal cell carcinoma is a complex group of highly heterogenous renal tumors demonstrating variable biological behavior. Pretreatment imaging of renal cell carcinoma involves accurate assessment of the primary tumor, presence of nodal, and distant metastases. CT and MRI are the key imaging modalities used in the staging of renal cell carcinoma. Important imaging features that impact treatment include tumor extension into renal sinus and perinephric fat, involvement of pelvicalyceal system, infiltration into adrenal gland, involvement of renal vein and inferior vena cava, as well as the presence of metastatic adenopathy and distant metastases. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Does renal tumor biopsies for small renal carcinoma increase the risk of upstaging on final surgery pathology report and the risk of recurrence?

BACKGROUND

Renal tumor biopsies (RTB) have been proposed as a means to diminish overtreatment of small renal masses. A potential concern of RTB is tumor seeding along the biopsy tract leading to worse clinical outcomes.

OBJECTIVES

To evaluate whether RTB was associated with greater upstaging to pT3a compared to patients without a biopsy and to determine if pathologic upstaging affects the risk of recurrence.

DESIGN, SETTING AND PARTICIPANTS

The Canadian Kidney Cancer information system was used to identify patients who underwent radical or partial nephrectomy for malignant renal tumors ≤ 4cm (cT1a) between January 1, 2011 and July 2, 2019.

INTERVENTION

RTB prior to nephrectomy or nephrectomy without biopsy.

OUTCOMES MEASUREMENTS AND STATISTICAL ANALYSIS

Upstaging to pT3a and cancer recurrence were compared between subjects that had a RTB compared to those who did not. A multivariable analysis was used to evaluate factors associated with disease upstaging and recurrence.

RESULTS AND LIMITATIONS

The cohort consisted of 1993 cT1a patients, followed for a median of 17.5 months. Of these patients, 502 (25%) had a preoperative RTB. There was no difference in the proportion with tumor upstaging to pT3a between patients that had RTB compared to those who did not (7.2% vs. 6.3%; P = 0.5). On multivariable analysis, RTB was not associated with pathological upstaging (Odds Ratio 0.90; 95% Confidence Interval 0.61-1.34) or recurrence (Odds Ratio 1.04; 95% Confidence Interval 0.57-1.89). The main limitation is that the study is underpowered to detect small differences between groups.

CONCLUSIONS

In this large, multi-institution cohort, RTB was not associated with increased risk of tumor upstaging or recurrence. Hence, tumor tract seeding, although possible, should not be a clinical deterrent to using RTBs as a means of personalizing renal masses management and diminishing overtreatment.

PATIENT SUMMARY

Recent evidence suggests that tumor seeding following RTB may be more common than initially perceived. Our results have demonstrated that RTB was not associated with an increased risk of tumor upstaging or disease recurrence.

Magnetic resonance imaging (MRI) of the renal sinus

This article presents methods to improve MR imaging approach of disorders of the renal sinus which are relatively uncommon and can be technically challenging. Multi-planar Single-shot T2-weighted (T2W) Fast Spin-Echo sequences are recommended to optimally assess anatomic relations of disease. Multi-planar 3D-T1W Gradient Recalled Echo imaging before and after Gadolinium administration depicts the presence and type of enhancement and relation to arterial, venous, and collecting system structures. To improve urographic phase MRI, concentrated Gadolinium in the collecting systems should be diluted. Diffusion-Weighted Imaging (DWI) should be performed before Gadolinium administration to minimize T2* effects. Renal sinus cysts are common but can occasionally be confused for dilated collecting system or calyceal diverticula, with the latter communicating with the collecting system and filling on urographic phase imaging. Vascular lesions (e.g., aneurysm, fistulas) may mimic cystic (or solid) lesions on non-enhanced MRI but can be suspected by noting similar signal intensity to the blood pool and diagnosis can be confirmed with MR angiogram/venogram. Multilocular cystic nephroma commonly extends to the renal sinus, however, to date are indistinguishable from cystic renal cell carcinoma (RCC). Solid hilar tumors are most commonly RCC and urothelial cell carcinoma (UCC). Hilar RCC are heterogeneous, hypervascular with epicenter in the renal cortex compared to UCC which are centered in the collecting system, homogeneously hypovascular, and show profound restricted diffusion. Diagnosis of renal sinus invasion in RCC is critically important as it is the most common imaging cause of pre-operative under-staging of disease. Fat is a normal component of the renal sinus; however, amount of sinus fat correlates with cardiovascular disease and is also seen in lipomatosis. Fat-containing hilar lesions include lipomas, angiomyolipomas, and less commonly other tumors which engulf sinus fat. Mesenchymal hilar tumors are rare. MR imaging diagnosis is generally not possible, although anatomic relations should be described to guide diagnosis by percutaneous biopsy or surgery.

Reassessing the current UICC/AJCC TNM staging for renal cell carcinoma

CONTEXT

The outcome prediction for renal cell cancer (RCC) remains controversial, and although many parameters have been tested for prognostic significance, only a few have achieved widespread acceptance in clinical practice. The TNM staging system defines local extension of the primary tumour (T), involvement of regional lymph nodes (N), and presence of distant metastases (M).

OBJECTIVE

This review focuses on reassessing the current TNM staging system for RCC.

EVIDENCE ACQUISITION

A literature search in English was performed using the National Library of Medicine database and the following keywords: renal cell cancer, kidney neoplasm, and staging. We scrutinized 1952 references, and 62 were selected for review based on their pertinence, study size, and overall contribution to the field.

EVIDENCE SYNTHESIS

The prognostic significance of tumour size for localized RCC has been investigated in a large number of studies. As a consequence, many modifications of the TNM staging system were primarily made to the size cut points between stage I and II tumours. The latest three revisions of the TNM system are systematically reviewed. For the heterogeneous group of locally advanced RCCs, involving different anatomic structures surrounding the kidney, the situation is still the subject of controversial scientific dispute. In detail, perirenal fat invasion, direct infiltration of the ipsilateral adrenal gland, invasion of the urinary collecting system, infiltration of renal sinus fat, and vena cava and renal vein thrombosis are disputed. Finally, staging of lymph node metastases and distant metastatic disease is discussed.

CONCLUSIONS

Special emphasis should be put on renal sinus invasion for stage evaluation. Retrospective studies relying on material collected at a time when no emphasis was placed on adequate sampling of the renal sinus should be treated with caution. In view of new treatment opportunities, the current TNM staging system of RCC and any other staging system must be dynamic.