Effects of switching from anastrozole to letrozole, due to reimbursement policy, on the outcome of breast cancer therapy

Background Endocrine therapy is one of the standard treatments for estrogen-receptor-positive breast cancer patients. Letrozole is the only aromatase inhibitor (AI) included in Thailand’s essential drug list since the change of reimbursement policy in 2008, when patients had to change their AIs (other than letrozole) to letrozole. This study aimed to prove that the efficacy of anastrozole plus letrozole is not less than anastrozole alone.