Advanced breast cancer in a patient achieving long-term SD after letrozole administration for liver metastasis developing during anastrozole therapy

We report a 69-year-old woman with breast cancer who was effectively treated with letrozole as a second-line therapy after becoming resistant to anastrozole. Her chief complaint at presentation was back pain. Physical examination and imaging studies showed a left breast tumor with skin invasion, multiple intramammary lesions, enlarged left axillary lymph node, and multiple bone metastases. Needle biopsy revealed invasive ductal carcinoma(scirrhous carcinoma)that was ER+/PgR+/ HER2-. The administration of anastrozole and bisphosphonate for 13 months resulted in a 33% reduction of the longest diameters of the breast tumors, but a liver metastasis developed. The treatment was changed to letrozole administration from January 2007.T he optimal effect of letrozole as determined by measurement on CT images was long-term SD maintained for about 13 months. No significant side effects were observed, and the QOL was favorable.