Survival Benefit of Tamoxifen in Estrogen Receptor-Negative and Progesterone Receptor-Positive Low Grade Breast Cancer Patients

PURPOSE: This study aimed to analyze the efficacy and prognostic significance of adjuvant tamoxifen in breast cancer patients with various hormone receptor statuses. METHODS: Typically, 1,260 female breast cancer patients were recruited in this study. The correlation between estrogen receptor (ER)/progesterone receptor (PR) phenotypes and clinical characteristics was investigated, and the survival rate was assessed after 5-year follow-up. RESULTS: The 5-year overall survival (85%) was better in women under the age of 50 years. Patients with ER+/PR+ tumors had a better 5-year survival rate (94%); those with ER-/PR- tumors experienced the worst outcome (74% survival rate); whereas single-positive cases were in between. In 97 out of 128 patients with ER-/PR+ tumors, tamoxifen was given as adjuvant hormonal therapy, and it increased the survival benefit in the lower grade group in terms of overall survival and disease-free survival (p=0.01 and p=0.03, respectively). CONCLUSION: For high-grade tumors with ER-/PR+, adjuvant tamoxifen therapy may have no survival benefit, whereas for the patients with low-grade ER-/PR+ tumors, adjuvant tamoxifen therapy is highly suggestive.