The natural history of breast cancer has not been fully elucidated, but physicians are making progress in the treatment of patients with this disease. Randomized, controlled trials indicate that screening, adjuvant systemic therapy, and adjuvant radiotherapy can reduce the risk for death caused by breast cancer. More importantly, national statistics show that breast cancer death rates are now decreasing (after remaining stagnant for nearly 40 years), but additional investigation into the natural history of breast cancer is clearly warranted. The randomized controlled trials on screening and local therapy, in particular, provide important insights into the natural history of the disease. Thus, the results of these trials should serve as a basis for additional investigation. Ultimately, a better understanding of the natural history of breast cancer may translate into improved treatments and better outcomes.