Proliferating cell nuclear antigen expression in Wilms' tumor: a comparative study of pre- and post-chemotherapy...

A total of 36 Wilms' tumors were immunohistochemically analyzed for proliferative (proliferating cell nuclear antigen-labeling) index (PI) with special reference to the effect of preoperative chemotherapy on the proliferative potential of tumors and differences in PI according to the histologic components (epithelial, blastemal and stromal). The cases were divided into two groups according to the status of chemotherapy at the time of surgical removal of the tumors. In group I (n = 12, cases with pre-operative chemotherapy), the mean PI +/- s.d. values of epithelial, blastemal and stromal types were 19.5 (n = 1), 10.1 +/- 5.28 (n = 8), and 16.2 +/- 13.49 (n = 3), respectively, and in group II (n = 24, cases without preoperative chemotherapy), 45.2 +/- 15.41 (n = 3), 28.5 +/- 16.92 (n = 10), and 23.2 +/- 4.45 (n = 2), respectively. The cases with mixed histology in group II (n = 9) had comparable PI values for each histologic component. The mean PI +/- s.d. was 12.1 +/- 7.76 in group I and 31.9 +/- 15.95 in group II. The PI value of group II was significantly higher than that of group I (P < 0.001). Alterations in the PI value following chemotherapy implied that the interpretation of tumor histology following chemotherapy should be more prudent because alteration of the PI, which reflects the proliferative potential of tumor cells, suggests modified biology of viable cells in pretreated cases as a consequence of chemotherapy.