[Preoperative grading of renal cell carcinoma by plasma immunosuppressive acidic protein level and tumor diameter using discriminant analysis].

To predict histological grade of renal cell carcinoma preoperatively, an equation using plasma immunosuppressive acidic protein (IAP) level and tumor diameter was proposed. Between April 1977 and December 1991, 281 patients, 195 males and 86 females, aged between 20 and 84-year-old, were operated at our institutions. Multivariate analysis was performed to detect relationship between tumor grade and various factors that have continuous quantity. Among plasma components tested, plasma IAP levels showed the best correlation with grade (r value = 0.526, n = 157). Tumor diameter also showed correlation with grade (r value = 0.476, n = 273). Therefore, these two factors were used as variates. Discriminant analysis was applied to differentiate the patients with grade 1 or grade 2 tumor from those with grade 3 ones. From this analysis the linear function was obtained; z = 6.9429 - 0.0048x1 - 0.4118x2 (x1: IAP (micrograms/ml), x2: diameter (cm)). Tumor was assumed to be grade 1 or grade 2 when z value was positive, and it was assumed to be grade 3 when z value was negative. Overall accuracy was 87.7%. Positive predictive value of grade 1 or grade 2 tumor, and grade 3 tumor was 91.7% and 77.8%, respectively. Sensitivity was 90.9% for grade 1 or grade 2 tumor, and 79.5% for grade 3 tumor. As a result, it's possible to estimate tumor grade before operation using discriminant analysis in patients with renal cell carcinoma.