Radiation sclerosing proliferative atypical nephropathy of peritumoral tissue of renal-cell carcinomas after the Chernobyl accident in Ukraine.

After the Chernobyl accident, the morbidity of renal-cell carcinomas in Ukraine increased gradually from 4.7 to 7.5 per 100,000 of the total population. Cesium 137 (137Cs) is responsible for 80-90% of the internal radioactivity in people living in radiocontaminated areas of Ukraine, and 90% of 137Cs is eliminated through the kidneys. Histological and immunohistochemical study of proliferating cell nuclear antigen (PCNA) and K-ras protein was performed in peritumoral kidney tissues of 167 Ukrainian patients (groups I-III, according to varying degrees of internal exposure to radiation), and of 85 analog Spanish patients, as a control group. Our data showed in the majority of Ukrainian patients a radiation sclerosing proliferative atypical nephropathy (RSPAN) in association with an increase in the incidences of tubular epithelial nuclear atypia and carcinoma in situ (CIS). Areas of epithelial nuclear atypia and CIS of the cortex and medulla showed significant PCNA expression with means of extent as 12, 14, and 15% of stained nuclei in groups I, II, and III respectively. K-ras expression of the same areas occurred in 67, 87, and 85% of cases in groups I, II, and III respectively. The present study points to a strong relationship between the long term of low-dose radiation exposure of the Ukrainian population and the development of RSPAN as a possible precursor of malignancy. In addition, it confirms the possible initiator, promoter, or progressor role of chronic low-level radiation of renal human carcinogenesis in Ukraine.