Uterine leiomyosarcoma has deregulated cell proliferation, but not increased microvessel density compared with uterine leiomyoma

Objective. To investigate the differences of biological aggressiveness in terms of proliferating cell nuclear antigen (PCNA) expression, cell proliferation, and microvessel density between uterine leiomyosarcoma and leiomyoma. Study design. All patients with uterine leiomyosarcoma undergoing surgery at National Cheng Kung University Hospital were eligible. Forty-four patients with uterine myoma were also studied as the benign counterpart. The paraffin-embedded slides were stained with hematoxylin and eosin to confirm the presence of tumor and to quantitate mitoses, PC 10 for measurement of PCNA expression, MIB 1 for measurement of cell proliferation, and factor VIII for quantitation of microvessel density. The immunohistochemical findings of the slides were correlated with clinicopathologic findings of the patients, and the data were analyzed by either χ² or unpaired t test. Results. Six patients with uterine leiomyosarcoma and 44 patients with uterine leiomyoma were studied. Statistically significant higher mean levels of PCNA and MIB 1 were observed in uterine leiomyosarcoma compared with those of uterine myoma (for PCNA expression, P = 0.0001; for MIB 1, 11.61 ± 11.42% vs 0.45 ± 0.21%, P < 0.0001). No significant difference of microvessel density was observed between these two groups (65.73 ± 48.62 vs 41.97 ± 28.20, P = 0.084). Among the six patients with leiomyosarcoma, two patients with a higher percentage of MIB 1-positive tumor cells died of recurrent disease. In contrast, two patients with lower MIB 1 counts were disease-free for 3 years or more. Conclusion. Deregulated cell growth in uterine leiomyosarcoma may account for the biological aggressiveness of this tumor. Furthermore, the percentage of MIB 1-positive tumor cells seems to be associated with the prognosis or extent of uterine leiomyosarcoma.