Table 2.

Studies of switching from one AI to another in postmenopausal women with HR⁺ breast cancer to address musculoskeletal symptoms

Study	N	Study design	Results	Reference
ALIQUOT	182	Open-label, crossover study 12 weeks of letrozole followed by 12 weeks of anastrozole, or 12 weeks of anastrozole followed by 12 weeks of letrozole	56% had joint problems on letrozole but not on anastrozole 55% had joint problems on anastrozole but not on letrozole	41,42
ATOLL	179	Prospective, nonrandomized, open-label, multicenter study Patients who discontinued anastrozole due to musculoskeletal symptoms initiated letrozole for 6 months or until discontinuation due to intolerance or disease progression	71.5% of patients on letrozole at 6 months 28.5% discontinued due to musculoskeletal symptoms	43
Yardley et al44	261	Patients who discontinued anastrozole due to grade 2 or 3 arthralgia/myalgia initiated letrozole for 6 months	87.4% of patients on letrozole at 6 months 9.6% discontinued due to arthralgia/myalgia	44

Abbreviations: AI, aromatase inhibitor; ALIQUOT, Anastrozole versus Letrozole: Investigation into Quality of Life and Tolerability; ATOLL, Articular Tolerance of Letrozole; HR⁺, hormone receptor-positive.