Prognostic variables to predict cancer-related death in incidental renal tumours.

OBJECTIVE: To identify, in a large multicentre series of incidental renal tumours, the key factors that could predict cancer-related deaths, as such tumours have a better outcome than symptomatic tumours and selected patients are increasingly being included in watchful-waiting protocols. PATIENTS AND METHODS: Data from 3912 patients were extracted from three international kidney-cancer databases. Age, gender, Eastern Cooperative Oncology Group (ECOG) performance status (PS), Tumour-Node-Metastasis (TNM) stage, tumour size, Fuhrman grade, and final pathology were recorded. Benign tumours and malignant lesions with incomplete information were excluded from final analysis. RESULTS: The mean (SD) age of the patients was 60.6 (12.2) years and the mean tumour size 5.5 (3.5) cm. Most tumours were malignant (90.2%) and of low stage (T1-T2, 71.7%) and low grade (G1-G2, 72.4%). There were nodal and distant metastases in 5.7% and 13% of the patients. In all, 525 (14.4%) patients died from cancer; in this group, tumours were >4 cm in 88.2% and had nodal or distant metastases in 20.2% and 49.3%, respectively. Multivariable analysis showed that tumour size >4 cm, ECOG PS >or=1, TNM stage and Fuhrman grade were independent predictors of cancer-related death. CONCLUSION: A significant proportion of incidental renal tumours can lead to the death of the patient. Standard prognostic variables for renal cell carcinoma appear to remain valid for this subset of patients. A watchful-waiting strategy should not be recommended if the tumour diameter is >4 cm, if biopsy confirms high-grade tumours, or if there is an impaired ECOG PS, or computed tomography findings suggest the presence of advanced T stage.