A comparison of four treatment strategies for ductal carcinoma in situ using decision analysis

BACKGROUND. The goals of the current study were to compare four treatment a pproaches in the management of ductal carcinoma in situ (DCIS), to determin e the conditions where mastectomy may be preferred to breast-conserving the rapy (BCT), and to determine conditions where the addition of tamoxifen pro duces better results than BCT alone. METHODS. A decision analysis model was used to compare four treatment appro aches after local excision for DCIS: mastectomy, irradiation, irradiation p lus adjuvant tamoxifen, or observation. The model weighed the potential ben efits of each treatment approach (reduction of ipsilateral and/or contralat eral breast carcinoma) against the potential risks of treatment-related tox icities. In addition, the model adjusted for the potential detrimental impa ct of local recurrence or treatment-related toxicity on health-related qual ity of life (HRQOL). Base-case estimates were obtained from published rando mized trial data. One-way and two-way sensitivity analyses were performed. RESULTS. According to the model, the optimal treatment for DCIS was strongl y dependent on the individual's risk of local recurrence and the patient's attitudes toward mastectomy. Mastectomy was preferred in patients whose est imated 10-year risk of local recurrence was > 15%, provided that mastectomy resulted in a very low reduction in quality of life (i.e., utility estimat e > 0.97). Conditions where the addition of tamoxifen was preferred to brea st-conserving therapy alone included the following: estimated 10-year risk of local recurrence > 38%, estimated 10-year risk of developing a contralat eral breast carcinoma > 6%, or a significant decrement in HRQOL associated with the development of an invasive local recurrence or salvage mastectomy (utility estimates < 0.85). CONCLUSION. Based on this quality-adjusted model, BCT appeared to be the pr eferred treatment for DCIS. The most important determinants of optimal mana gement for DCIS included the risk of local recurrence and the utility of ma stectomy. Formal evaluation of utilities in the context of DCIS and more ac curate determination of the risk of recurrence are required. Cancer 2001;92 :23-9. (C) 2001 American Cancer Society.