Combining Fulvestrant with Low-Dose Capecitabine is Effective and Tolerable in Woman with Metastatic Breast Cancer

Abstract

Although the use of endocrine therapy in combination with intravenous chemotherapy has not been standardized, the combination of fulvestrant and chemotherapy may be promising. A 62-year-old woman came to our hospital's outpatient clinic with extensive ascites. Approximately 10 years earlier, she had undergone mastectomy and sentinel lymph node biopsy. Pathologically invasive lobular carcinoma, with a maximum diameter of 28 mm, had been diagnosed in the left breast. The cancer had a histological grade of 2, was positive for estrogen receptor (95% or more positive cells), and was negative for both progesterone receptor (less than 1% positive cells) and human epidermal growth factor receptor 2. For 5 years the patient underwent adjuvant endocrine therapy with tamoxifen and then with anastrozole. Four years 2 months after adjuvant endocrine therapy had been completed, she felt abdominal distention, and her symptoms gradually worsened. A series of intensive examinations indicated that the invasive lobular carcinoma had metastasized to the peritoneum, pleura, uterus, and bone. Aromatase inhibitor was administered as a first-line therapy for the metastatic disease and was accompanied by denosumab injected every 28 days. For 2 months after the start of treatment with anastrozole, the ascites did not decrease and tumor markers increased. Because anastrozole had not been effective, fulvestrant (500 mg) and low-dose capecitabine (500 mg) were administered for the first 21 days of a 28-day cycle; this regimen had been shown by a phase 2 trial to be effective and tolerable in patients with metastatic breast cancer. The patient felt an improvement in abdominal distention, and the tumor markers decreased 2 weeks after the start of this combination therapy. By 10 months after the start of the combined therapy the ascites had decreased and pleural effusion had completely disappeared. The uterine wall became thinner, and the endometrial cavity became smaller. Tumor markers continued decreasing. No adverse events were observed. The combination of fulvestrant and low-dose capecitabine is promising because of its efficacy and tolerability for the treatment of patients with estrogen receptor-positive, human epidermal growth factor receptor 2-negative metastatic breast cancer.