Objective: This study aimed to evaluate the cost-effectiveness of postoperative adjuvant tamoxifen therapy using data from a Korean breast cancer registry.
Methods: In this retrospective, observational cohort study, patients were selected from the Korean Breast Cancer Society database. Women with stage I, II, or III breast cancer (diagnosed between 1981 and 2005), for whom information about tamoxifen use (20 mg/d for 5 years) and estrogen-receptor and/or progesterone-receptor status was available, were included. Cost-effectiveness was calculated from the perspective of Korean society. Using a decision analytic model based on standard clinical flow, incremental cost-effectiveness ratios (ICERs) for overall survival were calculated with stratification by disease stage and hormone-receptor status. One-way sensitivity analyses were also conducted. All results were represented as US dollars (US $1 approximately 1000 Korean won, in year-2005 values).
Results: A total of 17,579 patients were included in the analysis (10,694 tamoxifen users, 6885 nonusers). Among those with stage I or II breast cancer, ICERs for estrogen-receptor positive (ER+)/progesterone-receptor positive (PR+) tamoxifen users ranged from $739 to $1939. Tamoxifen use among those with either ER+ or PR+ status (but not both) remained cost-effective: $1217 to $3107 for 1 life-year gained. However, among estrogen-receptor negative (ER-)/progesterone-receptor negative (PR-) patients, tamoxifen use was more expensive and associated with shorter survival, and most ICERs were negative values, except for those aged >or=50 years (ICERs ranged from -$462 to -$3738 for 1 life-year gained). In contrast to those with stage I or II disease, tamoxifen use among patients with stage III disease was cost-effective regardless of hormone-receptor status. However, because of the small sample size, further studies are needed.
Conclusions: In this analysis, postoperative adjuvant tamoxifen use was cost-effective for stage I or II ER+ and/or PR+ breast cancer, but not for ER-/PR- disease. Tamoxifen therapy appeared to be cost-effective for patients with stage III breast cancer regardless of hormone-receptor status. Seoul National University Hospital identifier: C-0702-019-198.