In addition to the many international guidelines on the treatment of breast cancer, the Dutch Institute for Healthcare Improvement [Dutch acronym: CBO] has issued a Dutch national guideline on this subject, aided by representatives from the various medical professions involved and the patient advocacy group. A potential problem in reaching consensus on a practice guideline is the masking of controversies, which may hamper participation in new and innovative studies. Examples are the manner in which local and systemic treatments are combined and the consequences of new diagnostic modalities, for example the histopathologic presence of micrometastases in the sentinel node. The abridged version of the guideline published in this issue of the journal, scarcely allows space for specific problems such as the very young or old, pregnancy, hormonal substitution, male breast cancer and the patient with hereditary breast cancer. The authors of this guideline propose a nationwide registration of all patients plus follow-up to monitor the adherence to the guideline. The best way to study the quality of care and compliance with guidelines is still being debated in the medical literature. The money required for a nationwide registration of data on all patients including follow-up, might be better spent on measuring a number of indicators in a limited group of patients on the one hand and on devising new (randomised) trials on the other. This would result in the collection of better evidence for the many unanswered questions in the treatment of this common malignancy.