Long-term effect of fulvestrant for locally advanced breast cancer in an elderly patient - A case report

We report an elderly patient with locally advanced breast cancer who received long-term fulvestrant therapy. The patient was a 75-year-old woman who presented with a right breast lump. She noticed the tumor 4 years and 6 months ago, but she had not visited any hospital. However, her daughter brought her to our hospital. The tumor was 73 mm in diameter. A core needle biopsy for breast tumor led to a diagnosis of an invasive ductal carcinoma, positive for estrogen receptor (ER) and progesterone receptor (PgR), and negative for HER2/neu. The Ki-67 positive cell index was 20%. We performed a wholebody checkup, and confirmed the diagnosis as T4cN1M0, Stage IB. She initiated endocrine therapy by letrozole (2.5 mg/day). After 1 year and 6 months, tumor marker levels increased. We changed the endocrine therapy to fulvestrant (500 mg/month). For the next 2 years and 6 months, this therapy was effective. Her axillary lymph node metastases disappeared and tumor size decreased (60%). She underwent muscle-preserving mastectomy plus axillary lymph node dissection. The pathological diagnosis from the resected surgical specimen was confirmed as invasive ductal carcinoma, positive for ER and PgR, and negative for HER2/neu protein expression. The surgical margins were negative, and there was no metastasis in the lymph nodes. She was administered adjuvant endocrine therapy. Four years after surgery, she was well without metastasis.