Tamoxifen: a review of pharmacoeconomic and quality-of-life considerations for its use as adjuvant therapy in women with breast cancer.

Extensive clinical experience, summarised in the recent overview of the Early Breast Cancer Trialists' Collaborative Group (EBCTCG), have confirmed that tamoxifen reduces the rate of both disease recurrence and mortality when administered as adjuvant therapy in women with early breast cancer. Tamoxifen is now established as the preferred adjuvant agent in postmenopausal women; in particular, patients with node-positive, estrogen receptor-positive breast cancer have the most to gain from tamoxifen therapy. Data from a decision-analysis model indicated that tamoxifen monotherapy had a cost-utility ration {$US6000 per additional quality-adjusted life-year (QALY), in 1989 dollars} 5 to 6 times lower than that cited as the cost-acceptability cut-off point in the US. While tamoxifen monotherapy is effective in postmenopausal women, the EBCTCG overview findings indicate that a combined regimen of tamoxifen and antineoplastic chemotherapy has superior efficacy in the same patient group. An issue of current interest is whether the added benefit offered by such a regimen can be justified in terms of added toxicity and cost. Data from a decision-analysis model indicate that combined therapy has a high incremental cost-utility ratio ($US58 000 per additional QALY, in 1989 dollars) compared with no therapy in postmenopausal women. However, the quality-of-life measures TWiST (Time Without Symptoms and Toxicity) and Q-TWiST (quality-adjusted TWiST) indicate that the early toxicity associated with a combined regimen appears to be justified given the superior long term benefits. Patient preference data from 1 study further indicate that the degree of benefit offered by a combined regimen would be acceptable to the majority (73%) of patients. Other areas where pharmacoeconomic analyses may help define more closely the optimal use of adjuvant tamoxifen is in patients at low risk of developing metastatic disease and in determining the optimal duration of therapy. Both areas require further clinical data. In conclusion, tamoxifen adjuvant monotherapy has a low cost-utility ratio in postmenopausal women with node-positive, estrogen receptor-positive breast cancer. Combined therapy in the same patient group has a high cost-utility ratio compared with no therapy but quality-of-life and patient preference data suggest that the costs may be justified. Firm conclusions relating to the use of the drug in other patient subgroups and the optimal duration of therapy await further research.