Fulvestrant in heavily pretreated metastatic breast cancer: is it still effective as a very advanced line of treatment?

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.