Introduction

Cancers of the kidney are relatively uncommon, but a steadily increasing trend in both incidence and mortality has been reported.

Histology, classification and diagnosis

Most renal parenchymal tumors are adenocarcinomas. In the past, small tumors (<3 cm) were considered benign, but today, many believe that even small nodules are potentially malignant. New methods of diagnostic imaging have also increased accuracy of diagnosis with a possible impact on incidence. Malignant tumors of the renal pelvis are usually urothelial carcinomas, as in the bladder.

Nephroblastoma (Wilms' tumor) is a rare embryonal tumor of childhood with its own distinctive histological and cytogenic patterns.

Descriptive epidemiology

Incidence

Worldwide variation in these tumors is moderate, the highest rates (> 10) being seen in North America and Europe: in the male populations of Iceland (12.2), Sweden (11.3), and the Bas-Rhin department in France (11.0). Intermediate rates are seen in most remaining areas of the western world, rates being nearly identical in blacks and whites in the USA. Rates are very low in Chinese, Japanese, and Indians. Rates in Japanese and Chinese groups in the USA are, however, frequently higher. Renal pelvic cancer incidence usually reflects that of the parenchyma. However, high rates of renal pelvis and ureter cancer occur in regions where Balkan nephropathy is endemic (Castegnaro & Chernozemsky, 1987).