Attn: Macro - A randomized, open, parallel-group trial to compare the endocrine...

[Big Johnson]

From http://www.ncbi.nlm.nih.gov/entrez/...ve&db=PubMed&list_uids=10586340&dopt=Abstract

A randomized, open, parallel-group trial to compare the endocrine effects of oral anastrozole (Arimidex) with intramuscular formestane in postmenopausal women with advanced breast cancer.

Vorobiof DA, Kleeberg UR, Perez-Carrion R, Dodwell DJ, Robertson JF, Calvo L, Dowsett M, Clack G.

Sandton Oncology Centre, South Africa.

BACKGROUND: This study provides a direct randomized comparison of a new-generation, non-steroidal aromatase inhibitor, anastrozole (Arimidex), with a steroidal aromatase inhibitor (formestane) with respect to oestrogen (oestradiol, oestrone, and oestrone sulphate) suppression and tolerability. PATIENTS AND METHODS: Sixty postmenopausal women with advanced breast cancer were randomized to receive either anastrozole 1 mg once daily orally (n = 29), or formestane 250 mg once every two weeks by intramuscular injection (n = 31). Treatment was continued until progression of disease or withdrawal from the study. The primary endpoints of this study were oestradiol suppression and tolerability. The secondary endpoints included oestrone and oestrone sulphate suppression. All laboratory analyses were conducted 'blind' of the randomized drug treatment. RESULTS: Anastrozole produced a greater and more consistent suppression of oestradiol levels compared with formestane. Based on two- and four-week measurements, the mean fall from baseline (pre-dose) in oestradiol level was 79% and 58% in the anastrozole and formestane groups, respectively (P = 0.0001). After four weeks of treatment, oestrone and oestrone sulphate levels were also suppressed to a greater extent by anastrozole compared with formestane (oestrone: 85% versus 67%, respectively, P = 0.0043; oestrone sulphate: 92% versus 67%, respectively, P = 0.0007). No statistical differences were seen between the two drugs in the incidence of adverse events. CONCLUSIONS: Anastrozole provides a more consistent and significantly more effective suppression of oestradiol compared with formestane. Similar results were observed for oestrone and oestrone sulphate. The clinical significance of these differences in total oestrogen suppression remains to be established.

Publication Types:
Clinical trial
Multicenter study
Randomized controlled trial

PMID: 10586340 [PubMed - indexed for MEDLINE]

This doesn't say anything about permanent suppression, but it does conclude that arimidex is better short-term. I wonder how much formestane costs?

 

[Big Johnson]

Another, from http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9394856&dopt=Abstract

A randomised comparison of oestrogen suppression with anastrozole and formestane in postmenopausal patients with advanced breast cancer.

Kleeberg UR, Dowsett M, Carrion RP, Dodwell DJ, Vorobiof DA, Aparicio LA, Robertson JF.

The relative efficacy and tolerability of the aromatase inhibitors anastrozole (Arimidex) and formestane are assessed in a direct comparative trial in postmenopausal women with advanced breast cancer. Final results are available and reported here only for oestradiol suppression. Patients were randomised to receive either oral anastrozole, 1 mg once daily, or formestane, 250 mg every 2 weeks intramuscularly. In the anastrozole group, mean serum oestradiol levels fell from 32.1 pmol/l at baseline to 6.5 pmol/l at week 1, and similar levels of suppression were maintained over the next 3 weeks. In the formestane group, mean serum oestradiol levels fell from 31.0 pmol/l at baseline to 9.5 pmol/l at the week 1 assessment. In this group, serum oestradiol levels tended to rise by the 2- and 4-week measurements, i.e. immediately before the next injection was due. Based on the 2- and 4-week measurements, the mean falls in oestradiol levels were 79 and 58% in the anastrozole and formestane groups, respectively (p = 0.0001). More effective and consistent suppression of oestradiol was achieved with anastrozole at the therapeutic dose of 1 mg once daily, orally, than with formestane at the standard dose of 250 mg every 2 weeks, intramuscularly.

Publication Types:
Clinical trial
Randomized controlled trial

PMID: 9394856 [PubMed - indexed for MEDLINE]