These guidelines result from the continuing dedication and expertise of a large group of clinicians, scientists, patients, advocates and Health Canada staff who have worked at this now for over 4 years. Dr. Maurice McGregor chaired the Steering Committee on Clinical Practice Guidelines for the Care and Treatment of Breast Cancer, which crafted the first 10 guidelines. Dr. Mark Levine is the current chair. The entire project is supported both financially and logistically by Health Canada.

Breast cancer is an extremely active field of research. For the period Nov. 1, 1999, to Nov. 2, 2000, PubMed lists 3423 publications on breast cancer, of which 125 were randomized clinical trials. The intensity of this effort is good news for patients and clinicians, but it poses the challenge of assessing the validity and relevance of rapidly accruing research findings and of translating them into practical advice on what course of action to take at a particular moment for a particular patient. Authoritative, peer-reviewed consensus guidelines for treatment serve as a benchmark for best practice, providing guidance for clinicians and some degree of reassurance — and of empowerment — for patients.

However, if guidelines are to accomplish what they are designed to do, they must be kept current. In a rapidly developing field this means continual evaluation of the literature and continual revision of standards of practice. Thus, CMAJ will publish guideline "updates" in the form of brief commentaries that will outline revisions to previous recommendations and explain why these revisions were made. We will post the full text of the revised guideline on our Web site. For example, the steering committee has evaluated new clinical trial data on adjuvant systemic therapy for node-negative breast cancer and has modified guideline 7, originally published in the 1998 supplement.³ On page 213 of this issue, readers can review the new recommendations and the evidence on which they are based;⁴ the complete revised guideline can also be found online. Readers can also find the entire set of existing breast cancer guidelines online.