Stage I renal cell carcinoma. A clinicopathologic study of 82 cases.

Stage has been established as the most important predictor of prognosis in renal cell carcinoma. The predictive value of other morphologic features is less well established. Therefore, in this study we assessed morphologic parameters in 82 Robson stage I renal cell carcinomas. Insufficient numbers of T1 lesions were present in this series to permit a confident comparison of Robson staging with the Union Internationale Contre le Cancer-American Joint Committee on Cancer TNM (tumor, node, metastasis) staging. Morphologic parameters--including size, character of cytoplasm, nuclear grade, and pelvic invasion--were studied. Both univariate survival analysis and multivariate or tree-structured survival analysis (TSSA) were employed, with disease-free survival and actuarial survival as end points. Nuclear grade was the most important predictor of prognosis in stage I neoplasms by TSSA. Nuclear grade greater than 2 correlated with significantly shorter survival (p = 0.018). Stage I tumors measuring less than 5.0 cm by survival analysis (or 6.0 cm by TSSA) were associated with improved disease-free survival (p = 0.040), although TSSA indicated that the effect was pronounced only in low-grade neoplasms. The character of cell cytoplasm was not independent of nuclear grade (Kruskal-Wallis test, p = 0.028). The contingency table indicated disproportionate numbers of grade 4 mixed cell tumors, grade 3 granular cell tumors, and low-grade clear cell tumors. By TSSA, younger patients with low-grade but larger tumors had a poor clinical outcome. Elderly patients with high-grade tumors had the worst overall survival. None of the other clinical parameters or architectural pattern correlated with survival or disease-free survival. When nuclear grade was combined with tumor size and age at diagnosis in a decision tree, patients with stage I neoplasms were separated into favorable, intermediate, and poor prognosis groups.