Purpose and methods: We used decision analysis to model the natural history of breast cancer in hypothetical cohorts of 45-year-old women receiving tamoxifen, chemotherapy, or combined therapy. We used recurrence and efficacy data from the Early Breast Cancer Trialists' Collaborative Group (EBCTCG), utility values from focus groups, and costs from clinic charges and Medicare data.
Results: Tamoxifen alone provides minimal benefit in estrogen receptor-negative (ER-; 0.2 to 0.4 months) and modest benefit in receptor-positive (ER+; 3.5 to 5.2 months) cancer. Chemotherapy adds substantial benefit independent of receptor status (4.9 to 10.7 quality-adjusted months). In ER+ cancer, combined therapy adds an additional benefit (1.2 to 2.1 months) compared with chemotherapy alone. The incremental costs (United States dollars) necessary to add an additional year of life to the average woman ranged from $4,300 to $11,400 for tamoxifen alone for ER+ cancer, $4,900 to $11,400 for chemotherapy alone, and $14,800 to $33,100 for combined therapy.
Conclusion: In premenopausal early-stage breast cancer, chemotherapy adds substantial clinical benefit at a modest cost. Tamoxifen alone adds meaningful benefit only in ER+ cancer. Combined therapy is effective for all women, but is most beneficial and only cost-effective in ER+ women. If secondary effects of tamoxifen in reduction of cardiovascular and osteoporosis mortality are confirmed, then combined treatment may be optimal for all premenopausal women.