The large number of excellent presentations on breast cancer at this year's ASCO meeting reflects the enormous interest in clinical trials of this common disease. In the reports of adjuvant hormonal therapy, the most interesting included Abstract 273 by Boccardo et al., who reported that postmenopausal women with estrogen receptor positive (ER(+)) cancers who had already completed three years of tamoxifen experienced better overall survival if treated with two years of subsequent aminoglutethimide (a first-generation aromatase inhibitor) rather than another two years of tamoxifen. This whets our appetite for studies currently under way to define the role of third-generation aromatase inhibitors in the adjuvant setting. A report by FISHER: from the National Surgical Adjuvant Breast and Bowel Project B-23 study (Abstract 277) provided confirmation of what is rapidly becoming accepted, that the addition of tamoxifen to chemotherapy does not benefit breast cancer patients with negative lymph nodes who have ER(-) cancers. In premenopausal women, another report of the benefit of hormonal therapy, this time by the French Adjuvant Study Group using complete hormonal blockade with a luteinizing hormone-releasing hormone agonist and tamoxifen (Abstract 279) showed that hormonal therapy can be at least as good as, if not better, than six cycles of 5-fluorouracil 500 mg/m(2), epirubicin 50 mg/m(2), cyclophosphamide 500 mg/m(2) in terms of disease-free survival and overall survival. Among the papers on adjuvant chemotherapy, a controversial paper from the German Adjuvant Breast Cancer Group reported that three cycles of CMF (a dose-intense regimen with all three drugs being given on days 1 and 8) were as good as six cycles (Abstract 283). Another report, from the International Breast Cancer Study Group, raised the controversial question of whether there really is much added benefit from the addition of chemotherapy to tamoxifen in postmenopausal women with negative lymph nodes if their tumors have ERs (Abstract 281). A second study (the first was the CALGB study reported at ASCO in 1998) showing a benefit to the addition of Taxol to an anthracycline-based adjuvant regimen, was reported from the M.D. Anderson Cancer Center (Abstract 285), giving further impetus to the inclusion of Taxol in standard adjuvant treatment. Finally, there were a number of interesting presentations on HER-2. Reported here are three of these, all addressing the effect of HER-2 overexpression on the response to hormonal therapy. Taken together, they uphold the emerging concern that women with ER(+) cancers may not benefit significantly from endocrine treatment if the tumors also overexpress HER-2. Observations such as these will afford us the ability to predict more accurately which women will benefit from specific treatments.