Improved overall survival in postmenopausal women with early breast cancer after anastrozole initiated after treatment with tamoxifen compared with continued tamoxifen: the ARNO 95 Study.
OBJECTIVE
In postmenopausal women with estrogen receptor-positive early breast cancer, surgery is usually followed by a 5-year course of tamoxifen. This report presents results of a prospective, open-label, randomized study, designed to evaluate the benefits of switching to anastrozole after 2 years of tamoxifen treatment, compared with continuing on tamoxifen for 5 years.


METHODS
After receiving tamoxifen treatment for 2 years, eligible patients (n = 979) were randomly assigned to switch to anastrozole (1 mg/d) or continue tamoxifen (20 or 30 mg/d) for an additional 3 years. Patients were monitored every 6 months during years 1 to 3 and annually thereafter. The primary efficacy variable was disease-free survival, including local or distant recurrence, new contralateral breast cancer, or death. Secondary variables were overall survival and assessment of safety.


RESULTS
Switching to anastrozole resulted in a significant reduction in the risk of disease recurrence (hazard ratio [HR], 0.66; 95% CI, 0.44 to 1.00; P = .049), and improved overall survival (HR, 0.53; 95% CI, 0.28 to 0.99; P = .045) compared with continuing on tamoxifen. Fewer patients who switched to anastrozole reported serious adverse events (22.7% v 30.8%) compared with those who continued on tamoxifen, mainly due to more patients in the tamoxifen group with endometrial events. The overall safety profile for anastrozole was consistent with previous reports and no new safety issues were identified.


CONCLUSIONS
Postmenopausal women who have taken tamoxifen for 2 years as adjuvant therapy are less likely to experience a recurrence of breast cancer and have improved overall survival if they switch to anastrozole compared with continuing to receive tamoxifen.
Kaufmann
Manfred
M
Department of Obstetrics and Gynaecology, J.W. Goethe-University of Frankfurt, Frankfurt am Main, Frankfurt/Main, Germany. m.kaufmann@em.uni-frankfurt.de
Jonat
Walter
W
Hilfrich
Jörn
J
Eidtmann
Holger
H
Gademann
Günther
G
Zuna
Ivan
I
von Minckwitz
Gunter
G
D000368:Aged; D000077384:Anastrozole; D018931:Antineoplastic Agents, Hormonal / Q000008:administration & dosage*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000401:mortality / Q000517:prevention & control*; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008875:Middle Aged; D009570:Nitriles / Q000008:administration & dosage*; D017698:Postmenopause; D011446:Prospective Studies; D055502:Secondary Prevention; D013629:Tamoxifen / Q000008:administration & dosage*; D013997:Time Factors; D016896:Treatment Outcome; D014230:Triazoles / Q000008:administration & dosage*
D018931:Antineoplastic Agents, Hormonal; D009570:Nitriles; D014230:Triazoles; D013629:Tamoxifen; D000077384:Anastrozole