Disease burden and treatment outcomes in second-line therapy of patients with estrogen receptor-positive (ER+) advanced breast cancer: a review of the literature.

Objective: To determine the variable burden of disease of patients with advanced estrogen receptor-positive (ER+) breast cancer and assess the current treatment landscape after failure of first-line endocrine therapy.

Methods: A comprehensive literature review was performed (2000-2011) by searching Medline via PubMed, and Embase and Cochrane databases, to assess disease burden (i.e. societal, humanistic, and/or economic burden) and treatment landscape for second-line therapy of ER+ advanced breast cancer in postmenopausal women.

Results: Only 1 study was identified that evaluated burden of disease based on ER status (ER+, ER-negative, or ER-unknown); this study was a subgroup analysis assessing the impact of breast cancer recurrence over 10 years. The investigators reported that only minor differences in survival and medical costs were noted based on ER status in relapsing patients. Regardless of ER status, patients with breast cancer recurrence consumed more healthcare resources and were associated with more costly care than those without recurrence. A total of 7 studies were identified related to treatment outcomes of second-line therapy in ER+ patients. A combined international population totaled >3800 patients who had progressed on prior hormonal therapy, including tamoxifen and aromatase inhibitors. Three trials performed a comparative efficacy/safety assessment of an ER antagonist vs. aromatase inhibitor, 1 trial compared an aromatase inhibitor to megestrol acetate, and 1 trial compared 2 aromatase inhibitors. Among each of the studies evaluated, no significant differences were observed in the primary efficacy endpoint, and the safety profiles were similar. Two additional studies demonstrated a similar or better efficacy and safety profile based on different dosing evaluations.

Conclusions: Currently, there is insufficient evidence on the economic and humanistic burden associated with ER status, and this gap warrants further research. With increasing drug resistance and greater economic burden associated with breast cancer recurrence, there is an unmet medical need for improved treatment in this patient population.