Purpose: We validate the prognostic value of a symptom based classification (S classification) in a multi-institutional study.
Materials and methods: A total of 2,242 patients from 5 European centers were included in this study. Based on symptoms at diagnosis, patients were stratified into 3 groups of S1-asymptomatic tumors, S2-tumors with local symptoms and S3-tumors with systemic symptoms. Variables such as age, gender, tumor size, TNM stage, Fuhrman grade, Eastern Cooperative Oncology Group (ECOG) performance status, perinephric fat, renal vein and adrenal invasion were also considered for prognostic value. The end point of the study was cancer specific survival. Survival assessment was made with univariate and multivariate analyses using the Kaplan-Meier method and Cox regression analysis.
Results: Of the patients 1,018 (45.4%) were classified as S1, 865 (38.6%) S2 and 339 (16.0%) S3. The S classification correlated to tumor stage, grade and ECOG (p <0.001). On univariate analysis ECOG performance status, S classification, tumor size, TNM stage, Fuhrman grade, and adrenal, perinephric fat or vein invasion were significant prognostic factors (p <0.001). The S classification provided a significant prognostic stratification in the aggregate as well at each of the 5 centers. On multivariate analysis the S classification, TNM stage, Fuhrman grade, and perinephric fat and renal vein invasion remained independent prognostic factors (p <0.001).
Conclusions: This study confirms that it is possible to graduate symptoms for a prognostic purpose. The proposed symptom score should be evaluated for its integration in prognostic algorithms.