Efficacy of First-Line Letrozole Versus Tamoxifen as a Function of Age in Postmenopausal Women with Advanced Breast Cancer

Abstract

Materials and Methods. Nine hundred seven patients with advanced breast cancer were randomly assigned to receive 2.5 mg letrozole (n = 453) or 20 mg tamoxifen (n = 454) once daily in a double-blind, multicenter, international trial. Among the prospectively planned analyses were analyses of TTP and ORR by age (<70 and ≥70 years). The results of these prospectively planned analyses are reported here.Results. Letrozole was as effective in older postmenopausal women (≥70 years of age) as it was in younger postmenopausal women (<70 years of age). The overall ORR in the older subgroup was significantly higher in patients treated with letrozole (38%) than in patients treated with tamoxifen (18%). In the younger subgroup of postmenopausal patients, the ORRs were not significantly different (letrozole, 26%; tamoxifen, 22%). TTP was significantly longer for letrozole than for tamoxifen in both age groups (younger: letrozole median TTP, 8.8 months; tamoxifen, 6.0 months; older: letrozole median TTP, 12.2 months; tamoxifen, 5.8 months). Although age was independently prognostic of TTP, there was no significant effect of age on ORR in the presence of other factors.Conclusion. The data show that letrozole, 2.5 mg once daily, is as effective in older, postmenopausal women as it is in younger postmenopausal women with advanced breast cancer. In addition, letrozole was more effective than tamoxifen in both younger and older patients. The Oncologist 2004;9:497-506

Systematic review of aromatase inhibitors in the first-line treatment for hormone sensitive advanced or metastatic breast cancer

“…The full network included 4 unique studies comparing tamoxifen (20 mg/day) to letrozole [31][32][33][34][35][36][37][38][39][40], anastrozole (TARGET [30,[41][42][43] and North American [29,44] studies), and exemestane [45][46][47][48][49][50][51][52]. One study comparing anastrozole to tamoxifen (40 mg/day) [53] was excluded because the dosage was incomparable to dosages of tamoxifen used in the other studies.…”

Treatment of breast cancer in older women

“…While Tamoxifen may obtain 20Á30% ORRs, 50Á60% of clinical benefit, 6Á8 months of TTP, all other Selective Estrogen Receptor Modulators (SERMs) are less effective and cross-resistant [53]. AIs appeared equal to or more effective and better tolerated than tamoxifen in several randomized trials, even in older patients [88], and are widely accepted as first line therapy [82Á92]. (Table II).…”

Primary Systemic Therapy of Breast Cancer

“…In postmenopausal women with ER/PR-positive breast tumors, AIs have been proven to be superior to tamoxifen by improving time to progression in the metastatic setting [55][56][57] and DFS in the adjuvant setting [58][59][60]. Several randomized trials have compared preoperative AIs with tamoxifen.…”