Expression of Ki-67 as proliferation biomarker in imprint smears of endometrial carcinoma.

The aims of this study were to determine the expression of Ki-67 in type I and type II endometrial adenocarcinomas as well as normal endometrium in imprint smears and to correlate the results with clinicopathologic parameters of primary untreated endometrial cancer patients. During a 29-month period, 255 patients were evaluated with entometrial imprint cytology. Endometrial samples freshly resected from women who underwent total abdominal hysterectomy were studied. One hundred twenty-six patients had endometrial carcinoma and 129 cases were diagnosed as normal endometrium. The expression of Ki-67 was assessed by immunocytochemistry. Positive staining was correlated with increased stage, grade and lymph node metastases. High expression was more frequent in type II than type I endometrial adenocarcinoma and high-grade endometrial carcinoma had higher proportions of Ki-67 positive immunostaining compared with low-grade carcinoma. Proliferative endometrium showed high Ki-67 expression level, even higher than those of grade 1 and type I. On the other hand, secretory endometrium Ki-67 positive cells were markedly diminished and even disappeared. Completely negative staining was found to be related to atrophic endometrium. Immunocytochemical findings from Ki-67 stain, in addition to cytomorphologic features, appeared to be useful for the diagnosis of endometrial carcinoma in endometrial cytology with imprint smears. High Ki-67 expression correlates with morphologic features of aggressiveness and the expression pattern of Ki-67 correspond to the expected cyclic/atrophic pattern in normal endometrium.