Purpose: The goal of the computer program Adjuvant! is to allow health professionals and their patients with early breast cancer to make more informed decisions about adjuvant therapy.

Methods: Actuarial analysis was used to project outcomes of patients with and without adjuvant therapy based on estimates of prognosis largely derived from Surveillance, Epidemiology, and End-Results data and estimates of the efficacy of adjuvant therapy based on the 1998 overviews of randomized trials of adjuvant therapy. These estimates can be refined using the Prognostic Factor Impact Calculator, which uses a Bayesian method to make adjustments based on relative risks conferred and prevalence of positive test results.

Results: From the entries of patient information (age, menopausal status, comorbidity estimate) and tumor staging and characteristics (tumor size, number of positive axillary nodes, estrogen receptor status), baseline prognostic estimates are made. Estimates for the efficacy of endocrine therapy (5 years of tamoxifen) and of polychemotherapy (cyclophosphamide/methotrexate/fluorouracil-like regimens, or anthracycline-based therapy, or therapy based on both an anthracycline and a taxane) can then be used to project outcomes presented in both numerical and graphical formats. Outcomes for overall survival and disease-free survival and the improvement seen in clinical trials, are reasonably modeled by Adjuvant!, although an ideal validation for all patient subsets with all treatment options is not possible. Additional speculative estimates of years of remaining life expectancy and long-term survival curves can also be produced. Help files supply general information about breast cancer. The program's Internet links supply national treatment guidelines, cooperative group trial options, and other related information.

Conclusion: The computer program Adjuvant! can play practical and educational roles in clinical settings.