Recently, the Dutch Society for Medical Oncology published new consensus guidelines for the use of adjuvant systemic treatment in patients with operable breast cancer. We used data of the cancer registry of the Comprehensive Cancer Centre South to predict the change in the number of patients who will be candidates for systemic treatment according to these new guidelines. It was estimated that of all patients with operable breast cancer, 15% should receive chemotherapy, 27% hormonal therapy and 17% a combination of both modalities. Of the patients with negative axillary lymph nodes, one-third will receive adjuvant systemic treatment. Compared with the previous guidelines, the introduction of the new guidelines will cause a 50% increase in the number of patients receiving adjuvant systemic treatment in Dutch hospitals.