Reclassifying pT3 renal pelvic urothelial carcinoma with renal parenchyma invasion to pT2 improves correlation with overall survival

Contemporary Issues in Urothelial Carcinoma of Upper Urinary Tract

Upper urinary tract urothelial carcinoma (UTUC) is an uncommon malignancy involving the renal pelvis and ureter. Careful pathologic analysis plays a critical role in the diagnosis and clinical management of UTUC. In combination with clinical and radiologic evaluation, pathologic features can be used to stratify patients into low-risk and high-risk groups. This risk stratification can help clinicians select the optimal treatment for patients with UTUC, such as kidney-sparing (conservative) treatment, radical nephroureterectomy or ureterectomy, and perioperative systemic therapy. However, due to the technical difficulty of obtaining sufficient tissue from the upper urinary tract, it is often challenging for pathologists to accurately grade the tumor and assess tumor invasion in small biopsy specimens. Although the majority of UTUCs are pure urothelial carcinoma, a considerable subset of UTUCs show histologic subtypes or divergent differentiation. Recent studies have identified genetically distinct molecular subtypes of UTUC by examining DNA, RNA, and protein expression profiles. The prognosis of pT3 UTUC, particularly renal pelvic UC, remains controversial, and several studies have proposed subclassification of pT3 UTUC. Lynch syndrome is a significant risk factor for UTUC, and screening tests may be considered in young patients and those with familial histories of the disease. Despite significant progress in recent years, several issues remain to be addressed in the pathologic diagnosis, molecular classification, and treatment of UTUC.

Renal Pelvic Urothelial Carcinoma With Invasion Into Renal Medulla Can Be Redefined as pT2 to Improve Correlation With Survival

According to the American Joint Cancer Committee, pT3 renal pelvic carcinoma is defined as tumor invading the renal parenchyma and/or peripelvic fat and is the largest pT category, with notable survival heterogeneity. Anatomical landmarks within the renal pelvis can be difficult to discern. Using glomeruli as a boundary to differentiate renal medulla invasion from renal cortex invasion, this study aimed to compare patient survival of pT3 renal pelvic urothelial carcinoma on the basis of the extent of renal parenchyma invasion and, thereafter, determine whether redefining pT2 and pT3 improves pT correlation with survival. Cases with primary renal pelvic urothelial carcinoma were identified through a review of pathology reports from nephroureterectomies completed at our institution from 2010 to 2019 (n = 145). Tumors were stratified by pT, pN, lymphovascular invasion, and invasion of the renal medulla versus invasion of the renal cortex and/or peripelvic fat. Overall survival between groups was compared using Kaplan-Meier survival models and Cox regression multivariate analysis. pT2 and pT3 tumors had similar 5-year overall survival, with multivariate analysis demonstrating an overlap between hazard ratios (HRs) for pT2 (HR, 2.20; 95% CI, 0.70-6.95) and pT3 (HR, 3.15; 95% CI, 1.63-6.09). pT3 tumors with peripelvic fat and/or renal cortex invasion had a 3.25-fold worse prognosis than pT3 tumors with renal medulla invasion alone. Furthermore, pT2 and pT3 tumors with only renal medulla invasion had similar overall survival, whereas pT3 tumors with peripelvic fat and/or renal cortex invasion had a worse prognosis (P = .00036). Reclassifying pT3 tumors with only renal medulla invasion as pT2 yielded greater separation between survival curves and HR. Thus, we recommend redefining pT2 renal pelvic carcinoma to include renal medulla invasion and restricting pT3 to peripelvic fat and/or renal cortex invasion to improve the prognostic accuracy of pT classification.

The Stratification of Positive Lymph Nodes into pN1 and pN2 for Upper Urinary Tract Carcinoma is not Prognostically Significant

The 3^rd-7^th edition of the American Joint Committee on Cancer had 3 categories for positive lymph nodes (pN1-3) in upper urinary tract carcinoma. The 8^th edition removed pN3, defining pN1 as one lymph node with tumor deposit ≤ 2 cm and pN2 as a node with tumor deposit > 2 cm or metastases in multiple nodes. The aim of this study was to assess if the current pN categories impact survival in renal pelvic and ureteral carcinoma. Nephroureterectomies performed at our institution for primary upper urinary tract carcinoma between 2010-2019 were reviewed. Lymphadenectomy was performed in 73.3% of cases (151/206, median 9 nodes). Eighty-one (53.6%) patients were deceased at last review [pN0, 53 (44.5%); pN1-2, 28 (87.5%)]. There was no difference in overall or recurrence free survival between pN1 and pN2 with 5-year overall survival (95% confidence interval) of pN0, 60.7% (52.0-70.8%); pN1, 15.4% (4.3-35.2%); and pN2, 21.1% (8.8-40.3%). The metastatic deposit size threshold of 2 cm, number of positive lymph nodes, as well as extranodal extension did not correlate with overall or recurrence free survival. As such, pN1 and pN2 were grouped together with a 5-year overall survival of 18.8% (9.12-28.6%). The current stratification of upper urinary tract carcinoma into pN1 and pN2 does not provide prognostic information, and both yield a stage IV classification, regardless of pT or pM category. Therefore, we recommend further simplification of pN classification into one category for regional lymph node metastasis, irrespective of lymph node deposit size or number of positive lymph nodes.

Urothelial Carcinoma: Update on Staging and Reporting, and Pathologic Changes Following Neoadjuvant Chemotherapies

Staging and reporting of cancers of the urinary tract have undergone major changes in the past decade to meet the needs for improved patient management. Substantial progress has been made. There, however, remain issues that require further clarity, including the substaging of pT1 tumors, grading and reporting of tumors with grade heterogeneity, and following NAC. Multi-institutional collaborative studies with prospective data will further inform the accurate diagnosis, staging, and reporting of these tumors, and in conjunction with genomic data will ultimately contribute to precision and personalized patient management.