In the phase II CALGB 40903/Alliance trial reported in the Journal of Clinical Oncology, E. Shelley Hwang MD, MPH, and colleagues found that preoperative letrozole was associated with beneficial imaging and biomarker changes in postmenopausal women with estrogen receptor (ER)-positive ductal carcinoma in situ (DCIS).
E. Shelley Hwang MD, MPH
The multicenter study involved 67 women with ER-positive DCIS without invasion who completed 6 months of letrozole at 2.5 mg/day and had breast magnetic resonance imaging (MRI) data for all study timepoints. MRIs were to be obtained at baseline, 3 months, and 6 months. The primary endpoint was change in 6-month MRI enhancement volume compared with baseline.
MRI and Biomarker Changes
Baseline MRI volumes ranged from 0.004 to 26.3 cm3, with a median volume of 1.4 cm3. Median reductions from baseline were 0.6 cm3 (61.0%) at 3 months (P < .001) and 0.8 cm3 (71.7%) at 6 months (P < .001).
ER H-score, progesterone receptor (PR) H-score, and Ki67 were assessed at baseline and at surgical excision after letrozole treatment. The ER H-score decreased by a median of 15 points, from a median of 228 (P = .005); the PR H-score decreased by a median of 85 points, from a median of 15 (P < .001); and the Ki-67 score decreased by a median of 6.3% from a median of 12.0% (P = .007).
Among the 59 patients who underwent surgery per study protocol, residual DCIS persisted in 50 patients (85%), invasive cancer was detected in 6 (10%), and no residual DCIS or invasive cancer was observed in 9 (15%).
The investigators concluded, “In a cohort of postmenopausal women with ER-positive DCIS, preoperative letrozole resulted in significant imaging and biomarker changes. These findings support future trials of extended endocrine therapy as primary nonoperative treatment of some [patients with] DCIS.”
Disclosure: The study was supported by the National Cancer Institute and The Breast Cancer Research Foundation. For full disclosures of the study authors, visit ascopubs.org.The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.