Initial therapy

A large randomized trial of 9,366 patients compared the use of the AI anastrozole and the combination of anastrozole and tamoxifen with tamoxifen alone as adjuvant therapy for postmenopausal patients with lymph node–negative or lymph node–positive disease. Most (84%) of the patients in the study were hormone receptor–positive. Slightly more than 20% had received chemotherapy.[61]; [62][Level of evidence B1]

A large randomized trial of 9,366 patients compared the use of the AI anastrozole and the combination of anastrozole and tamoxifen with tamoxifen alone as adjuvant therapy for postmenopausal patients with lymph node–negative or lymph node–positive disease. Most (84%) of the patients in the study were hormone receptor–positive. Slightly more than 20% had received chemotherapy.[61]; [62][Level of evidence B1]

With a median follow-up of 33.3 months, no benefit in DFS was observed for the combination arm relative to tamoxifen alone.[61]

A large randomized trial of 9,366 patients compared the use of the AI anastrozole and the combination of anastrozole and tamoxifen with tamoxifen alone as adjuvant therapy for postmenopausal patients with lymph node–negative or lymph node–positive disease. Most (84%) of the patients in the study were hormone receptor–positive. Slightly more than 20% had received chemotherapy.[61]; [62][Level of evidence B1]

Patients on anastrozole, however, had a significantly longer DFS (HR, 0.83) than those on tamoxifen. In an analysis conducted after a median follow-up of 100 months among hormone receptor–positive patients, DFS was significantly (P = .003) longer in patients on anastrozole (HR, 0.85; 95% CI, 0.76–0.94), but OS was not improved (HR, 0.97; 95% CI, 0.86–1.11; P = .7).[62]

A large randomized trial of 9,366 patients compared the use of the AI anastrozole and the combination of anastrozole and tamoxifen with tamoxifen alone as adjuvant therapy for postmenopausal patients with lymph node–negative or lymph node–positive disease. Most (84%) of the patients in the study were hormone receptor–positive. Slightly more than 20% had received chemotherapy.[61]; [62][Level of evidence B1]

Patients on tamoxifen more frequently developed endometrial cancer and cerebrovascular accidents, whereas patients on anastrozole had more fracture episodes. The frequency of myocardial infarction was similar in both groups. Except for a continued increased frequency of endometrial cancer in the tamoxifen group, these differences did not persist in the posttreatment period.[62]

A large, double-blind, randomized trial of 8,010 postmenopausal women with hormone receptor–positive breast cancer compared the use of letrozole with tamoxifen given continuously for 5 years or with crossover to the alternate drug at 2 years.[63] An updated analysis from the International Breast Cancer Study Group (IBCSG-1-98 [NCT00004205]) reported results on the 4,922 women who received tamoxifen or letrozole for 5 years at a median follow-up of 51 months.[64][Level of evidence B1]

A large, double-blind, randomized trial of 8,010 postmenopausal women with hormone receptor–positive breast cancer compared the use of letrozole with tamoxifen given continuously for 5 years or with crossover to the alternate drug at 2 years.[63] An updated analysis from the International Breast Cancer Study Group (IBCSG-1-98 [NCT00004205]) reported results on the 4,922 women who received tamoxifen or letrozole for 5 years at a median follow-up of 51 months.[64][Level of evidence B1]

DFS was significantly superior in patients treated with letrozole (HR, 0.82; 95% CI, 0.71–0.95; P = .007; 5-year DFS, 84.0% vs. 81.1%).

A large, double-blind, randomized trial of 8,010 postmenopausal women with hormone receptor–positive breast cancer compared the use of letrozole with tamoxifen given continuously for 5 years or with crossover to the alternate drug at 2 years.[63] An updated analysis from the International Breast Cancer Study Group (IBCSG-1-98 [NCT00004205]) reported results on the 4,922 women who received tamoxifen or letrozole for 5 years at a median follow-up of 51 months.[64][Level of evidence B1]

OS was not significantly different in patients treated with letrozole (HR, 0.91; 95% CI, 0.75–1.11; P = .35).

In a meta-analysis, which included 9,885 women from multiple trials, the 10-year recurrence risk was 19.1% in the AI group versus 22.7% in the tamoxifen group (RR, 0.80; 95% CI, 0.73–0.88; P < .001). The overall 10-year mortality rate was also reduced from 24.0% to 21.3%. (RR, 0.89; 95% CI, 0.8–0.97; P = .01).[60][Level of evidence A2]