[Efficacy of sequential treatment with anastrozole following exemestane compared with exemestane following anastrozole in patients with metastatic breast cancer].
BACKGROUND
There are three third-generation aromatase inhibitors (AI) available in Japan. Though it is supposed that they can be administered sequentially because of their little cross-resistant effect, it is not definite which sequential treatment is best.


OBJECTIVE
To examine retrospectively the difference in efficacy by the AI sequence when anastrozole ( ANA) and exemestane (EXE) are clinically administered sequentially for patients with metastatic breast cancer.


METHODS
We examined 22 patients with metastatic breast cancer administered ANA alone as first-line AI treatment, EXE alone as second-line (A--> E group), and 13 patients given EXE alone as first-line AI treatment (E --> A group) since December 2002 in our hospital.


METHODS
In the A --> E and E --> A group, we examined overall response rate, clinical benefit (CB) rate, time to progression (TTP) for the first- and second-line treatment, respectively, overall survival (OS) after starting AI and successive efficacy of the two AIs.


RESULTS
There were no significant differences between the two groups in patient characteristics and history of prior treatments. Overall response rate of the first-line treatment in the A--> E and the E--> A group was 31.8% and 38.5%, and the CB rate was 68.2% and 53.8%, respectively. Overall response rate of the second-line treatment in the A --> E (22 cases) and the E --> A (3 cases) group was 13.6% and 0%, and the CB rate was 36.4% and 33.3%, respectively, reflecting no particular differences. In the A --> E group, five (33.3%) among 15 cases obtained CB by EXE and three (42.6%) among 7 cases who did not obtain CB by ANA did so by EXE. Also, in the E--> A group, one among 3 cases who did not obtain CB by EXE did so by ANA. No significant differences were observed in TTP and OS between the two groups.


CONCLUSIONS
When ANA and EXE are administered sequentially, no particular difference in efficacy occurs due to the sequence. In some cases, 2 agents become effective successively, and cases resistant to first-line treatment can expect efficacy from second-line treatment. Sequential treatment with the two agents seems to provide very significant efficacy in clinical practice regardless of the order of administration.
Ikeda
Masahiko
M
Dept. of Breast and Thyroid Surgery, Kawasaki Medical School.
Kurebayashi
Junichi
J
Sonoo
Hiroshi
H
Miyake
Akiko
A
Nomura
Tsunehisa
T
Yamamoto
Yutaka
Y
Shiiki
Shigeo
S
Nakashima
Kazutaka
K
Tanaka
Katsuhiro
K
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000077384:Anastrozole; D000730:Androstadienes / Q000627:therapeutic use*; D047072:Aromatase Inhibitors / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology*; D005260:Female; D006801:Humans; D008875:Middle Aged; D009362:Neoplasm Metastasis / Q000188:drug therapy / Q000473:pathology; D009570:Nitriles / Q000627:therapeutic use*; D012189:Retrospective Studies; D015996:Survival Rate; D014230:Triazoles / Q000627:therapeutic use*
D000730:Androstadienes; D047072:Aromatase Inhibitors; D009570:Nitriles; D014230:Triazoles; D000077384:Anastrozole; C056516:exemestane