EURURO Vol. 71 No. 4

665 692

Kidney Cancer
Application of the Stage, Size, Grade, and Necrosis (SSIGN) Score
for Clear Cell Renal Cell Carcinoma in Contemporary Patients
William P. Parker John C. Cheville Igor Frank Harras B. Zaid Christine M. Lohse
Stephen A. Boorjian Bradley C. Leibovich R. Houston Thompson
a Department of Urology, Mayo Clinic, Rochester, MN, USA; bDepartment of Pathology, Mayo Clinic, Rochester, MN, USA; c Department of Health Services
Research, Mayo Clinic, Rochester, MN, USA
ava ilable at
journal homepage:
Article info
Article history:
Accepted May 25, 2016
Associate Editor:
Giacomo Novara
Keywords:
Partial nephrectomy
Prognosis
Radical nephrectomy
Renal cell carcinoma
Survival
Abstract
Background: The tumor stage, size, grade, and necrosis (SSIGN) score was originally
defined using patients treated with radical nephrectomy (RN) between 1970 and
1998 for clear cell renal cell carcinoma (ccRCC), excluding patients treated with partial
nephrectomy (PN).
Objective: To characterize the original SSIGN score cohort with longer follow-up and
evaluate a contemporary series of patients treated with RN and PN.
Design, setting, and participants: Retrospective single-institution review of 3600 con-
secutive surgically treated ccRCC patients grouped into three cohorts: original RN,
contemporary (1999–2010) RN, and contemporary PN.
Intervention: RN or PN.
Outcome measurements and statistical analysis: The association of the SSIGN score with
risk of death from RCC was assessed using a Cox proportional hazards regression model,
and predictive ability was summarized with a C-index.
Results and limitations: The SSIGN scores differed significantly between the original RN,
contemporary RN, and contemporary PN cohorts (p < 0.001), with SSIGN 4 in 53.5%,
62.7%, and 4.7%, respectively (p < 0.001). The median durations of follow-up for these
groups were 20.1, 9.2, and 7.6 yr, respectively. Each increase in the SSIGN score was
predictive of death from RCC (hazard ratios [HRs]: 1.41 for original RN, 1.37 for
contemporary RN, and 1.70 for contemporary PN; all p < 0.001). The C-indexes for
these models were 0.82, 0.84, and 0.82 for original RN, contemporary RN, and contem-
porary PN, respectively. After accounting for an era-specific improvement in survival
among RN patients (HR: 0.53 for contemporary vs original RN; p < 0.001), the SSIGN
score remained predictive of death from RCC (HR: 1.40; p < 0.001).
Conclusions: The SSIGN score remains a useful prediction tool for patients undergoing
RN with 20-yr follow-up. When applied to contemporary RN and PN patients, the score
retained strong predictive ability. These results should assist in patient counseling and
help guide surveillance for ccRCC patients treated with RN or PN.
Patient summary: We evaluated the validity of a previously described tool to predict
survival following surgery in contemporary patients with kidney cancer. We found that
this tool remains valid even when extended to patients significantly different than were
initially used to create the tool.
# 2016 European Association of Urology. Published by Elsevier B.V. All rights reserved.
* Corresponding author. Department of Urology, Mayo Clinic, 200 First Street SW, Rochester, MN
55905, USA. Tel. +1 507 266 9968; Fax: +1 507 284 4951.
E-mail address: (R.H. Thompson).
0302-2838/# 2016 European Association of Urology. Published by Elsevier B.V. All rights reserved.