Objectives: To assess the effect of renal cell carcinoma (RCC) subtype, tumor size, and Fuhrman grade on clinical outcome in patients with pathologic T1 (pT1) RCC treated with radical nephrectomy.
Methods: Between 1970 and 1998, 840 patients underwent radical nephrectomy for pT1 RCC. Tumors were subtyped and graded. Univariate and multivariate Cox proportional hazards models were fitted to assess the features associated with metastasis-free survival (MFS) and cancer-specific survival (CSS). We identified a range of tumor sizes of clear cell RCC in which a transition occurred from low to high risk. Cox proportional hazards models were then fitted by using size cutoffs.
Results: The mean follow-up (+/- SD) was 9.4 +/- 6.6 years among the patients alive at latest follow-up. At 10 years, the CSS and MFS for clear cell RCC (n = 682) were 89.1% and 88.6%, respectively; for papillary RCC (n = 122), they were 95.5% and 93.8%; and for chromophobe RCC (n = 33), they were both 100%. The differences in CSS (P = 0.013) and MFS (P = 0.023) between clear cell RCC and the other subtypes were statistically significant. For clear cell RCC, tumor size and Fuhrman grade were independently associated with CSS and MFS (P <0.001). A transition in risk occurred for tumor sizes between 4.5 and 5.0 cm, and the tumor size cutoff of 5.0 cm had the highest concordance index for predicting CSS and MFS.
Conclusions: RCC subtype is a strong independent prognostic variable for patients with pT1 RCC treated with radical nephrectomy. For clear cell RCC, Fuhrman grade and tumor size are independently associated with CSS and MFS.