Well Differentiated (Grade 1) Clear Cell Renal Carcinoma

Abstract

Clinic experience from 1950-1980 with cases of grade 1 clear cell renal carcinoma were reviewed to determine whether patients with well differentiated clear cell renal tumors had the favorable clinical course that has been demonstrated for those with well differentiated oncocytic renal tumors. Of the 46 patients identified with pure grade 1 clear cell renal carcinoma, 2/3 were discovered incidentally during diagnostic tests for unrelated complaints. These tumors generally were small, with 67% being .ltoreq. 6 cm in diameter. Of all tumors, 83% were pathologic stage 1 (confined within the renal capsule). Ten patients have died of metastatic renal carcinoma, and 3 are alive with disease. Actuarial survival curves show a significantly poorer prognosis for patients with grade 1 clear cell renal tumors compared to patients with grade 1 oncocytic renal tumors or to an age and sex-matched control group. Whereas well differentiated oncocytic renal tumors behave like benign renal tumors, well differentiated clear cell renal tumors can behave like aggressively malignant renal carcinomas and should be treated as such.