Can the Kattan nomogram still accurately predict prognosis in renal cell carcinoma using the revised 2010 tumor-nodes-metastasis reclassification?
The Kattan nomogram has been used in renal cell cancer to predict progression-free survival after nephrectomy. Tumor-nodes-metastasis staging is essential for the calculation of this score. The effect of the recent 2010 revision to the tumor-nodes-metastasis classification on the predictive ability of the Kattan nomogram was studied. All patients having radical nephrectomy for renal cell cancer in the 5-year period of 2004-2008 at a tertiary referral center were included. Pathological and radiological records were reviewed to identify tumor-nodes-metastasis stage (2002 and 2010 classifications). Kattan scores were calculated for the 2002 and 2010 tumor-nodes-metastasis stages, and the effect on survival predictions were compared with actual outcomes. A total of 291 patients with non-metastatic renal cell cancer were identified. Revision of the tumor-nodes-metastasis staging from the 2002 to 2010 classification resulted in an increase in the number of patients with stage pT3a (from 30 to 75), a reduction in the patients with stage pT3b (from 57 to 10) and a small increase in stage pT4 cases (1 to 3). This altered the proportion of patients in the Kattan prognostic of "good" (from 61% to 69%), "intermediate" (from 29% to 22%) and "poor" (from 10% to 8%). The overall median predicted 5-year progression-free survival was 79.8% with 2002 tumor-nodes-metastasis, and 81.8% with 2010 tumor-nodes-metastasis. Actual 5-year progression-free survival was 83.0%, which was not significantly different from that predicted using either tumor-nodes-metastasis classification (P = 0.66). On comparing the new 2010 and old 2002 tumor-nodes-metastasis classification in our cohort, we showed the predictive ability of the Kattan nomogram remained unaltered.