Postmenopausal women who progress on fulvestrant ('Faslodex') remain sensitive to further endocrine therapy.
OBJECTIVE
This retrospective evaluation of data from two randomized, multicenter trials examined whether tumor responses to further endocrine therapy were seen in postmenopausal women with advanced breast cancer who had progressed on both initial endocrine therapy, usually tamoxifen, and on the estrogen receptor (ER) antagonist fulvestrant ('Faslodex').


METHODS
A combined total of 423 patients received fulvestrant 250 mg as a monthly intramuscular injection. After progression on fulvestrant, some patients received another endocrine therapy. Responses to subsequent endocrine therapy were assessed using a questionnaire sent to the trial investigators. Best responses were classified as a complete or partial response (CR or PR), stable disease (SD) lasting > or = 24 weeks, or disease progression.


RESULTS
Follow-up data were available for 54 patients who derived clinical benefit (CB, defined as CR, PR or SD) from fulvestrant and who received subsequent endocrine therapy, resulting in a PR in 4 patients, SD in 21 patients, and disease progression in 29 patients. Data were available for 51 patients who derived no CB from fulvestrant and who received further endocrine therapy, resulting in a PR in 1 patient, SD in 17 patients, and disease progression in 33 patients. Aromatase inhibitors were used as subsequent endocrine therapy in > 80% of patients.


CONCLUSIONS
After progression on fulvestrant, patients may retain sensitivity to other endocrine agents. Fulvestrant provides an additional option to existing endocrine therapies for the treatment of advanced or metastatic breast cancer in postmenopausal women, and may provide the opportunity to extend the sequence of endocrine regimens before cytotoxic chemotherapy is required.
Vergote
I
I
Department of Gynecologic Oncology, University Hospitals, Leuven, Belgium. Ignace.Vergote@uz.kuleuven.ac.be
Robertson
J F R
JF
Kleeberg
U
U
Burton
G
G
Osborne
C K
CK
Mauriac
L
L
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000077384:Anastrozole; D000735:Androstenedione / Q000031:analogs & derivatives* / Q000627:therapeutic use; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use*; D047072:Aromatase Inhibitors; D001943:Breast Neoplasms / Q000188:drug therapy*; D018450:Disease Progression; D004311:Double-Blind Method; D015536:Down-Regulation; D019008:Drug Resistance, Neoplasm; D004791:Enzyme Inhibitors / Q000627:therapeutic use*; D004958:Estradiol / Q000031:analogs & derivatives* / Q000627:therapeutic use*; D020847:Estrogen Receptor Modulators / Q000627:therapeutic use*; D005260:Female; D005500:Follow-Up Studies; D000077267:Fulvestrant; D006801:Humans; D000077289:Letrozole; D019290:Megestrol Acetate / Q000627:therapeutic use; D008875:Middle Aged; D009570:Nitriles / Q000627:therapeutic use; D017698:Postmenopause; D012189:Retrospective Studies; D016879:Salvage Therapy; D016896:Treatment Outcome; D014230:Triazoles / Q000627:therapeutic use
D018931:Antineoplastic Agents, Hormonal; D047072:Aromatase Inhibitors; D004791:Enzyme Inhibitors; D020847:Estrogen Receptor Modulators; D009570:Nitriles; D014230:Triazoles; D000077267:Fulvestrant; D000077384:Anastrozole; D000735:Androstenedione; D004958:Estradiol; D000077289:Letrozole; C014594:formestane; D019290:Megestrol Acetate