Cell Proliferation Measured by Ki67 Staining and Correlation to Clinicopathological Parameters in Operable Breast Carcinomas from Vietnamese and Swedish Patients

Background : Cell proliferation measured by Ki67 has recently been shown to be a prognostic and predictive factor in breast cancer. The aim of this study was to compare cell proliferation determined by Ki67 expression with different clinicopathologic parameters among Vietnamese and Swedish women with breast cancer. Materials and Methods : The study was based on series of breast cancer from Vietnamese patients treated in the National Cancer Hospital in Hanoi, Vietnam and from Swedish patients treated in the Karolinska Hospital, Stockholm, Sweden. Cell proliferation was measured by Ki67 staining in an automated procedure and was expressed as percentage of stained tumor cell nuclei. Results : The distribution and mean of Ki67 indices from Vietnamese patients were similar to those estimated from Swedish patients, 27.7% (±17.1%) vs. 26.9% (±23.1%). There were no differences between the two series of patients with respect to proliferation index and age, tumor size and lymph node status. The mean Ki67 indices were higher in high grade tumors in both series. In addition, Swedish patients had significantly higher Ki67 indices in tumors associated with other poor prognostic factors as compared to Vietnamese, 52.8% vs. 31.9% in ER(-) tumors, 39.6% vs. 30.7% in PgR(-) tumors and 40.1% vs. 28.3% in HER2 amplified tumors, respectively. Conclusions : The cell proliferation index in breast cancers was similar in the Vietnamese and Swedish series. High proliferation was associated with poor prognostic factors such as high grade, hormone receptor negativity and HER2 amplification.