When a difficult problem leads to recurring questions in clinical practice, prudent doctors develop a well-supported answer that will address most of the questions asked by their patients. What determines when or how often this clinical assessment should be updated? Should one review every new paper on the subject, or wait until the next systematic review has been published? Would annual review of each "practice position" be timely enough or too time-consuming? Of course, how often one updates depends on the type of question and the strength of the supporting evidence. The pressure to keep up intensifies when the question involves both a common intervention and a worrying adverse effect, as in the case of the possible association between Hormone Replacement Therapy (HRT) and breast cancer incidence. What do we know now? HRT is frequently prescribed for postmenopausal women. Breast cancer is the most common cancer in this group, and the most common cause of death among women 40 to 50 years of age. Any possibility of a link between HRT and breast cancer would be of serious concern.