Identification of patients with hormone receptor-positive breast cancer who need adjuvant tamoxifen therapy for more than 5 years

Background/purpose: Extended hormonal therapy with tamoxifen for > 5 years has improved disease-free survival (DFS) and overall survival (OS) in hormone receptor (HR)-positive breast cancer patients. The aim of this study was to identify the HR-positive breast cancer women who need adjuvant tamoxifen for > 5 years. Methods: Between 1990 and 2004, 1104 HR-positive breast cancer patients who had received tamoxifen treatment at our institution and had been disease free for at least 6 years were included in this analysis. Univariate and multivariate analyses of prognostic factors for late recurrence were performed using the binary logistic regression model. Results: During a median follow-up period of 10.9 years after surgery, 70 patients died and 99 showed recurrence. In multivariate analysis, age < 40 years (p < 0.001) and lymph node metastasis (p < 0.001) were associated with higher rates of recurrence. We stratified patients into high-risk (age < 40 years or positive lymph node status, 536 patients) and low-risk (age > 40 years and negative lymph node status, 566 patients) groups. The recurrence rates were 14.6% and 3.5% in the high-risk and low-risk groups, respectively. Patients in the high-risk group had poorer disease-free survival (p < 0.001) and overall survival (p = 0.010) than those in the low-risk group. Conclusion: Our findings suggest that HR-positive breast cancer women either aged < 40 years or with positive lymph node status were justified in continuing with tamoxifen therapy for > 5 years.