The estrogen suppression after sequential treatment with formestane in advanced breast cancer patients.
In postmenopausal patients, estrogens have an important role in breast cancer growth and aromatase inhibitors (AI) suppress the aromatase enzyme system which converts androgens into estrogens. The aim of this study was to evaluate the effect on estrogen suppression of formestane 250 mg i.m. fortnightly, given immediately after the failure of a previous treatment with non-steroidal AI. Twenty-two advanced breast cancer patients progressing on letrozole, anastrozole and aminoglutethimide entered the study. At the beginning of the study, the serum estrogen levels were suppressed by the previous treatment with non-steroidal AI, and the following treatment with formestane moderately maintained this suppression; in four patients serum estrogen levels increased fivefold after 10 weeks. Neither complete nor partial responses were observed; 11 patients (50%) showed a stable disease lasting > or = 6 months, and the median time to progression was 6 months (range 3-9 months). No correlation was observed between clinical responses and serum estrogen suppression. Tolerability was satisfactory, and no patient withdrew from the study due to adverse events. In conclusion, formestane has demonstrated a moderate activity in estrogen suppression, and there is evidence that, at the failure of a previous treatment with non-steroidal AI, the sequential use of steroidal AI is feasible. This approach can be used in clinical practice in order to offer a disease control with a satisfactory quality of life.
Zilembo
Nicoletta
N
Medical Oncology Unit B, Istituto Nazionale per lo Studio e la Cura dei Tumori, via G. Venezian 1, 20133 Milan, Italy.
Bajetta
Emilio
E
Bichisao
Ettore
E
Martinetti
Antonia
A
La Torre
Ignazia
I
Bidoli
Paolo
P
Longarini
Raffaella
R
Portale
Tindara
T
Seregni
Ettore
E
Bombardieri
Emilio
E
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000735:Androstenedione / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use*; D018931:Antineoplastic Agents, Hormonal / Q000009:adverse effects / Q000494:pharmacology / Q000627:therapeutic use*; D047072:Aromatase Inhibitors; D001943:Breast Neoplasms / Q000188:drug therapy*; D004958:Estradiol / Q000097:blood*; D004965:Estrogen Antagonists / Q000494:pharmacology / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D007273:Injections, Intramuscular; D008875:Middle Aged; D017698:Postmenopause; D011959:Receptors, Estradiol / Q000378:metabolism
D018931:Antineoplastic Agents, Hormonal; D047072:Aromatase Inhibitors; D004965:Estrogen Antagonists; D011959:Receptors, Estradiol; D000735:Androstenedione; D004958:Estradiol; C014594:formestane