Background: Over 75% of postmenopausal patients with metastatic breast cancer have hormone receptor-positive tumors. Endocrine therapy, with its more favorable toxicity profile than chemotherapy, is the preferred treatment modality for these patients.
Objectives: To assess our experience with fulvestrant, an antiestrogen, in an advanced phase of treatment, after progression on the classical anti-estrogen (tamoxifen) and aromatase inhibitors
Methods: The study group comprised 46 patients with metastatic breast cancer treated with fulvestrant during the years 2002-2006. Fulvestrant was given monthly until disease progression or unacceptable toxicity.
Results: The median number of fulvestrant cycles was 4.14 (range 1-32). Four patients are still on the treatment. The reasons for treatment discontinuation include disease progression (n=40), refusal (n=1), and allergic reaction (n=1). Ten patients (22%) achieved partial response and 22 (47%) had stable disease. Fourteen (30%) had disease progression with a response rate of 22% and a clinical benefit of 67%, and 14 (30%) had stable disease for > 6 months. Twenty-five patients (54%) are still alive, 4 (9%) without and 21 (45%) with disease progression. With a median follow-up of 15 months (range 1-30.1), the median time to progression was estimated to be 4 months (95% confidence interval 3.1-4.9), and the estimated overall survival 20.1 (95% CI 13.6 to upper limit; not reached yet). The 1 year estimated survival is 67%.
Conclusions: In terms of late-phase administration, fulvestrant still appears to have a good clinical effect, with a time to progression of 4 months and a clinical benefit > 60%, notably accompanied by only very mild toxicity. Irrespective of the line of treatment the patients received, the 4 month time to progression was constant and the medication was still working effectively in a very late line of treatment in metastatic breast cancer. Fulvestrant offers clinical benefit with very mild toxicity in a very heavily pretreated population and the medication is recommended, even in patients who received many lines of chemotherapy.