Elsevier

European Urology

Volume 73, Issue 5, May 2018, Pages 772-780
European Urology

Platinum Priority – Kidney Cancer
Editorial by Umberto Capitanio, Alessandro Larcher, Francesco Montorsi and Pierre Karakiewiczc on pp. 781–782 of this issue
Predicting Oncologic Outcomes in Renal Cell Carcinoma After Surgery

https://doi.org/10.1016/j.eururo.2018.01.005Get rights and content

Abstract

Background

Predicting oncologic outcomes is important for patient counseling, clinical trial design, and biomarker study testing.

Objective

To develop prognostic models for progression-free (PFS) and cancer-specific survival (CSS) in patients with clear cell renal cell carcinoma (ccRCC), papillary RCC (papRCC), and chromophobe RCC (chrRCC).

Design, setting, and participants

Retrospective cohort review of the Mayo Clinic Nephrectomy registry from 1980 to 2010, for patients with nonmetastatic ccRCC, papRCC, and chrRCC.

Intervention

Partial or radical nephrectomy.

Outcome measurements and statistical analysis

PFS and CSS from date of surgery. Multivariable Cox proportional hazards regression was used to develop parsimonious models based on clinicopathologic features to predict oncologic outcomes and were evaluated with c-indexes. Models were converted into risk scores/groupings and used to predict PFS and CSS rates after accounting for competing risks.

Results and limitations

A total of 3633 patients were identified, of whom 2726 (75%) had ccRCC, 607 (17%) had papRCC, and 222 (6%) had chrRCC. Models were generated for each histologic subtype and a risk score/grouping was developed for each subtype and outcome (PFS/CSS). For PFS, the c-indexes were 0.83, 0.77, and 0.78 for ccRCC, papRCC, and chrRCC, respectively. For CSS, c-indexes were 0.86 and 0.83 for ccRCC and papRCC. Due to only 22 deaths from RCC, we did not assess a multivariable model for chrRCC. Limitations include the single institution study, lack of external validation, and its retrospective nature.

Conclusions

Using a large institutional experience, we generated specific prognostic models for oncologic outcomes in ccRCC, papRCC, and chrRCC that rely on features previously shown—and validated—to be associated with survival. These updated models should inform patient prognosis, biomarker design, and clinical trial enrollment.

Patient summary

We identified routinely available clinical and pathologic features that can accurately predict progression and death from renal cell carcinoma following surgery. These updated models should inform patient prognosis, biomarker design, and clinical trial enrollment.

Introduction

Renal cell carcinoma (RCC) represents a common urologic malignancy, with almost 64 000 cases and 14 400 deaths expected in 2017 [1]. While there is a strong association between pathologic stage and the risk of death [2], stage alone is insufficient to inform prognosis for most patients. Indeed, it has been shown that beyond American Joint Committee on Cancer (AJCC) stage other important factors to consider include manner of presentation, histology, grade, and associated findings such as the presence of histologic tumor necrosis or sarcomatoid features [3], [4], [5]. This variability in the behavior of RCC suggests the need for better methods to guide prognostication following surgery.

To this end, there have been numerous preoperative and postoperative nomograms designed for different outcomes in RCC [4], [5], [6], [7], [8], [9], [10]. Unfortunately, there are limitations with this myriad of models for risk prediction. Perhaps the most significant limitations have been the use of AJCC staging as a predictor of outcome and the failure to consider primary histology. While staging of RCC has been relatively constant, over the lifetime of the AJCC staging manual there have been subtle changes—such as the subdivision of cT1 into cT1a and cT1b with the advent of the seventh edition [11]—in the staging of RCC, which raises questions about the long-term applicability of models based on a given AJCC staging edition. Furthermore, while some models have been validated, their clinical utility has been limited by a dearth of functional tools for application in routine practice. Lastly, and most importantly, risk models to date have largely focused on clear cell RCC (ccRCC), neglecting the significant subset of patients with nonclear cell histologies [12]. Therefore, we sought to generate prognostic models for progression and death from RCC, accounting for all major histologic subtypes, and to operationalize these models into an easy-to-use clinical application.

Section snippets

Materials and methods

After obtaining Institutional Review Board approval, the Mayo Clinic Nephrectomy Registry was queried to identify binephric patients treated with radical or partial nephrectomy between 1980 and 2010 for sporadic, unilateral, nonmetastatic RCC. Clinical features abstracted included age at surgery, year of surgery, sex, race, presence of symptoms at diagnosis, smoking status, body mass index, Eastern Cooperative Oncology Group performance status, Charlson comorbidity score, preoperative estimated

Results

A total of 3633 patients were identified, of whom 2726 (75%) were diagnosed with ccRCC, while 607 (17%) had papRCC, and 222 (6%) had chromophobe (chrRCC). Of the remaining patients (excluded from analysis), clear cell papillary RCC was present in 32 (1%), RCC not otherwise specified in 31 (1%), collecting duct in seven (< 1%), and other rare subtypes in eight (< 1%). Clinicopathologic features for ccRCC, papRCC, and chrRCC are summarized in Table 1.

Discussion

Using a large institutional experience with RCC, we have generated prognostic models for each of the three most common RCC subtypes—ccRCC, papRCC, and chrRCC. These models are based on routine clinicopathologic information that is readily available following surgical resection and that does not rely upon the current AJCC staging manual. These models performed well, with excellent discrimination, and retained their ability to stratify patients by outcomes after accounting for the competing risk

Conclusions

Using a large institutional experience with pathologic rereview, we identified features associated with progression and death from RCC that are specific to histologic subtype and take into account known differences in predictive features within a given histology. Furthermore, our model does not rely on current AJCC staging, a purposeful choice in order to limit obsolescence as updated staging guidelines are put forth. Finally, each model had excellent discrimination, stratified patient

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