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Preoperative endocrine therapy improves outcomes for certain women with DCIS
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SAN ANTONIO — Six months of preoperative endocrine therapy appeared safe and effective among postmenopausal women with ER-positive ductal carcinoma in situ, according to data from the phase 2 open-label single-arm multicenter CALGB 40903 Alliance trial presented at the San Antonio Breast Cancer Symposium.
MRI volume decreased substantially by 3 months, although mammographic extent of diseasedid not significantly change.
“Our data demonstrate that preoperative aromatase inhibitors can be safe when used for ER-positive postmenopausal DCIS,” Eun-Sil Shelley Hwang, MD, MPH, vice-chair of research, chief of the section of breast surgery, and professor of surgery and radiology at Duke University School of Medicine, said during her presentation. “Patients can benefit from aromatase inhibitors because it may allow breast conservation in those who present as marginal candidates.”
Although the standard regimen for DCIS includes surgery and frequently adjuvant radiation therapy or endocrine therapy, some experts say this approach represents overtreatment for certain patients.
For this reason, Hwang and colleagues assessed whether primary endocrine therapy alone would lead to measurable radiographic changes among postmenopausal women with unresected ER-positive DCIS.
Change in total MRI volume of DCIS enhancement from baseline to 3 months and from baseline to 6 months served as the study’s primary endpoint. Secondary endpoints included change in MRI maximum diameter over baseline and change in mammographic extent of disease over baseline.
Eligible patients underwent mammography at baseline, followed by 6 months of letrozole preoperative therapy. The researchers obtained follow-up breast MRI at 3 months and 6 months.
Sixty-six women completed letrozole treatment per protocol and were assessable between August 2012 and February 2016. An additional two patients who did not complete treatment per protocol were considered assessable and included in the final cohort of 68 patients (mean age, 63 years).
Most patients (81%) had ER- and PR-positive DCIS. Nearly half (47%) of women had an intermediate DCIS nuclear grade, whereas 40% had high and 10% had low DCIS nuclear grade.
Although researchers did not observe a significant difference in tumor volume between 3 months and 6 months, the total mean MRI volume decreased from baseline to 3 months by 1.93 cm (P < .001) and from baseline to 6 months by 1.82 cm (P < .001).
Researchers observed a decrease in mean total mammographic tumor diameter by 3.31 mm² from baseline to 6 months.
Regarding surgical treatment, Hwang noted that more than 80% of women underwent lumpectomy, three women had mastectomy, and 20% with various indications underwent sentinel node evaluation.
“Importantly, nine patients included in the study declined surgery,” Hwang said. “We continue to follow these patients and, because of the very short follow-up at the time of this presentation, we do not have a confidence report for these patients who did not undergo surgery. We also have a quality-of-life component of the trial, which we will be reporting on very soon.” – by Jennifer Southall
Reference:
Hwang ES, et al. Abstract GS5-05. Presented at: San Antonio Breast Cancer Symposium; Dec. 5-9, 2017; San Antonio.
Disclosures: Hwang reports no relevant financial disclosures. Please see the abstract for all other authors’ relevant financial disclosures.