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During the 25-year period subsequent to the Chernobyl accident, the morbidity of malignant renal tumors in Ukraine has increased from 4.7 to 10.7 per 100,000 of the total population. Recent studies of our group have shown that increases in morbidity, aggressiveness, and proliferative activity of renal cell carcinomas (RCCs), especially clear-cell renal cell carcinoma (CCRCC), in Ukrainian patients continuously inhabiting the radio-contaminated areas could be explained by specific molecular changes influenced by the so-called "chronic persistent low-dose ionizing radiation" (CPLDIR) exposure. This study aimed to examine the role of angiogenesis in CCRCC carcinogenesis associated with CPLDIR in patients living more than 20 years in cesium 137 ((137)Cs) contaminated areas after the Chernobyl accident in Ukraine. Paraffin-embedded specimens of 106 CCRCs were studied: Control cases were 18 tumors from Spanish patients (group 1), 25 tumors from Ukrainian patients from so-called clean areas without known radio-contamination (group 2), and 63 tumors from Ukrainian patients from radio-contaminated areas (group 3). For intratumoral microvessel density (MVD) determination, anti-CD31 antibody was used. A computerized image analysis program was used to quantitatively calculate the vascular density. Seventy-three percent of group 3 and 72 % of group 2 CCRCCs displayed the highest MVD. A striking increase in MVD was seen in group 3 CCRCCs, in comparison with groups 1 and 2 (p < 0.001). The majority of the hot spot vessels in group 3 was poorly differentiated. Moreover, MVD values for total vessels as well as for capillaries and tumor grade were strongly correlated. When we compared only tumor-node-metastasis tumor stages I and II, the differences remained statistically significant (p < 0.1). The ratio of the average total vessels and capillaries in the Ukrainian groups combined was 1.65:1 in comparison to the Spanish group. Our results provide evidence that CPLDIR exposure increases MVD (particularly capillary) in CCRCCs and is associated with a higher histological grade.

During the 13-year period subsequent to the Chernobyl accident, the morbidity of malignant renal tumors in Ukraine has increased from 4. 7 to 7.5 per 100,000 of total population. Cesium 137 ((137)Cs) accounts for 90% of the incorporated radioactivity in the Ukrainian population, which has been exposed to long-term, low dose ionizing radiation and 90% of the more labile pool of ((137)Cs) is excreted via kidneys. The present study was performed to evaluate the histopathological features and the immunohistochemical status of proliferating cell nuclear antigen (PCNA) and K-ras in renal cell carcinomas (RCCs) of 236 Ukrainian patients (groups I to V), which represents a varying degrees of internal exposure to radiation and were operated in 2 different periods of time after the Chernobyl accident. The control group VI of 112 analog patients with RCCs was selected in Spain. The strong significant differences between the Ukrainian and Spanish groups were found in tumoral nuclear grade, in the percentage of sarcomatoid changes, the level of the peritumoral inflammatory response as well as in the peritumoral lesions. The dramatic increase of aggressivity and proliferative activity supported by strong PCNA and K-ras expression of RCCs from Ukrainian groups, associated with chronic radiation nephropathy of peritumoral kidney tissue, showed good correlation with the duration of radiation exposure and confirmed the influence of chronic but regular and sustained low dose of ionizing radiation on renal carcinogenesis of the Ukrainian population., (Copyright 2000 Wiley-Liss, Inc.)