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 approaches in the management of ductal carcinoma in situ (DCIS), to determine the conditions where mastectomy may be preferred to breast-conserving therapy (BCT), and to determine conditions where the addition of tamoxifen produces better results than BCT alone. METHODS: A decision analysis model was used to compare four treatment approaches after local excision for DCIS: mastectomy, irradiation, irradiation plus adjuvant tamoxifen, or observation. The model weighed the potential benefits of each treatment approach (reduction of ipsilateral and/or contralateral breast carcinoma) against the potential risks of treatment-related toxicities. In addition, the model adjusted for the potential detrimental impact of local recurrence or treatment-related toxicity on health-related quality of life (HRQOL). Base-case estimates were obtained from published randomized trial data. One-way and two-way sensitivity analyses were performed. RESULTS: According to the model, the optimal treatment for DCIS was strongly dependent on the individual's risk of local recurrence and the patient's attitudes toward mastectomy. Mastectomy was preferred in patients whose estimated 10-year risk of local recurrence was > 15%, provided that mastectomy resulted in a very low reduction in quality of life (i.e., utility estimate > 0.97). Conditions where the addition of tamoxifen was preferred to breast-conserving therapy alone included the following: estimated 10-year risk of local recurrence > 38%, estimated 10-year risk of developing a contralateral 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 preferred treatment for DCIS. The most important determinants of optimal management for DCIS included the risk of local recurrence and the utility of mastectomy. Formal evaluation of utilities in the context of DCIS and more accurate determination of the risk of recurrence are required.