Prognostic validity of neoplastic cells with notable nuclear atypia in endometrial cancer.

To investigate how the architectural grade of endometrial adenocarcinoma should be adjusted in the presence of neoplastic cells with notable nuclear atypia in order to assign the histologic grade. Four hundred seventy-six patients with stage I endometrial cancer (endometrioid type) who were surgically treated in a single institute formed the study population. The architectural grade and the proportion of tumor cells with notable nuclear atypia were examined for each case. The effects of notable nuclear atypia on the disease-free survival of each architectural grade were analyzed. The disease-free survival of architectural grade 1 and grade 2 tumors was significantly affected and was worse than that of architectural grade 3 tumors when more than 25% of the tumor cells showed notable nuclear atypia. Tumors that had 26% to 50% of neoplastic cells with notable nuclear atypia showed a similar probability of recurrence as did tumors that had more than 50% of neoplastic cells with notable nuclear atypia. The series suggests that the upgrading of architectural grade 1 or 2 tumors, in which more than 25% of the neoplastic cells show notable nuclear atypia, into a grade 3 tumor may be more practical than upgrading by one architectural grade 1 or 2 tumors, in which the majority of neoplastic cells show notable nuclear atypia.