Prolonged time to progression with fulvestrant for metastatic breast cancer

Abstract

Although the incidence of breast cancer has been declining in recent years, the disease is still one of the leading causes of cancer deaths in women. Recently, breast cancer has been treated with innovative approaches that use hormone-sensitive therapies. This is because in at least one-third of breast cancers, estrogens mediated via the estrogen receptor pathway act as endocrine growth factors. Fulvestrant has been studied as both first- and second-line therapy for locally advanced and metastatic breast cancer, but few studies have shown its effect as third-line therapy alone. To observe the disease time to progression (TTP) obtained with fulvestrant when used on metastatic breast cancer as first-, second-, and also third-line therapy. We also aimed to correlate the TTP obtained with fulvestrant with hormone receptor, HER2 expression, and metastatic site. This was a cohort study that retrospectively examined medical records of 73 postmenopausal women with advanced breast cancer who were treated with fulvestrant (250 mg/month i.m. injection) and followed at the Department of Medical Oncology at Hospital do Cancer A. C. Camargo in São Paulo, Brazil from August 2003 to December 2006. The median TTP with fulvestrant was about 11 months. When used as the first-line therapy, TTP was about 13 months; when used as second-line, TTP was about 6 months; and when used as third-line, it was about 12 months. No statistically significant difference was observed regarding the therapy line. In patients with positive ER tumors, TTP was 11 months. No significant difference in TTP was observed in negative ER tumors (TTP = 10 months). In patients with positive PgR tumors, TTP was 13 months and for negative PgR, TTP was 6 months (P = 0.008). According to the HER2 status, the TTP was 5 months for HER2+ and 10 months for HER2-. Our findings indicate that fulvestrant is an effective alternative for treatment of metastatic breast cancer.