This subanalysis is published alongside two large double-blind, placebo-controlled randomised phase 3 trials that compared the effect of anastrozole with tamoxifen for preventing breast cancer recurrence in postmenopausal women with locally excised ER-positive ductal carcinoma in situ.
A commentary discusses whether the findings of these studies allow the conclusion to be drawn that all women with locally excised ductal DCIS should be offered adjuvant endocrine therapy, and if so, should it be an aromatase inhibitor or tamoxifen? It notes that neither trial provide any clues about which subgroup of patients with ER-positive DCIS might benefit most from which drug, though most women with locally excised disease already have an excellent prognosis, as shown by the rarity of events in both trials. However, the commentator warns that local recurrence of invasive breast cancer after a diagnosis of DCIS is linked to an increased risk of death, and requires more extensive surgery and the addition of systemic therapy, which might include chemotherapy, therefore prevention of invasive recurrence or new contralateral disease is an important goal in disease. He suggests that for premenopausal or perimenopausal women, tamoxifen should remain the endocrine therapy of choice. For postmenopausal women aged younger than 60 years, an aromatase inhibitor could offer more protection after excision of ER-positive DCIS, but with different tolerability to tamoxifen.