Usefulness of Ki-67 as a prognostic factor in lymph node-negative breast cancer / 한국유방암학회지

ABSTRACT

PURPOSE: To evaluate the independent prognostic value of Ki-67 in lymph node-negative breast cancer and the usefulness of Ki-67 when it combined with St. Gallen classification as a guidance of adjuvant chemotherapy for node-negative cancer. METHODS: We retrospectively reviewed the data of 534 patients with lymph node-negative breast cancer who underwent curative surgery between 1998 and 2001 at our institution. Patients were classified according to the guideline of risk groups of St. Gallen consensus and the level of Ki-67 expression. Distant metastasis-free survival (DFS) rates were compared between groups. RESULTS: With a median follow-up of 55 months, the overall 5-year DFS rate was 91.5%. The 5-year DFS rates for patients with high and low Ki-67 tumors (cut-off value > or = 10%) were 84.6% and 93.7%, respectively (p < 0.001). In a Cox regression model involving potential prognostic factors, high Ki-67 expression could independently predict the risk of distant recurrence (odds ratio = 2.0 [95% confidence interval, 1.03-3.93]). The 5-year DFS rates for patients with average and minimal risk group of St. Gallen classification were 89.3% and 97.5%, respectively. The average risk group was further divided into two subgroups with significantly different prognosis according to the Ki-67 expression (DFS rate 84.2% vs. 91.5%; p = 0.007). CONCLUSIONS: Ki-67 was an independent prognostic factor in lymph node-negative breast cancer and the combination of Ki-67 expression and the St. Gallen classification could provide a more useful therapeutic guideline for lymph node-negative breast cancer patients.