A Case of Complete Response to Letrozol Treatment in a Postmenopausal Woman With Breast Cancer Who has Progressed After Multiple Lines of Chemotherapy.

Approximately 60% of all breast cancers are endocrine dependent. Postmenopausal patients who have positive hormone receptor status are eligible for aromatase inhibitor treatment. Letrozole is a potent, selective, non-steroidal, third-generation aromatase inhibitor which reduces oestrogen biosynthesis approximately 99% at the dose of 2.5 mg/day. We report a 54-years-old female patient diagnosed with grade 2 invasive ductal carcinoma of the breast. She received adjuvant chemotherapy, followed by 5 years of tamoxifen. After 8 years, recurrence appeared in lung, supraclavicular lymph nodes and brain. She had many cycles of cytotoxic chemotherapeutic agents, trastuzumab and lapatinib previously. After the progression (lung and brain), palliative therapy was thought due to very poor performance status of the patient. (ECOG: 3) Letrozole was added in the treatment and we obtained near-complete remission from her lung and brain metastasis with 2.5 mg/day dose of letrozole. This study might support successfully use of aromatase inhibitors in patients who has been previously treated with multiple lines of chemotherapy and had still progressive disease.