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William J. Gradishar, MD, FACP, FASCO
William J. Gradishar, MD, FACP, FASCO
Posted: Monday, February 24, 2025
Adjuvant tamoxifen may reduce the risk of breast cancer recurrence in patients with “good-risk” ductal carcinoma in situ (DCIS) who undergo breast-conserving surgery but forgo radiation, according to research presented at the 2024 San Antonio Breast Cancer Symposium (SABCS; Abstract GS2-02). Jean L. Wright, MD, of the University of North Carolina and the Lineberger Comprehensive Cancer Center, Chapel Hill, and colleagues found that tamoxifen significantly decreased the risk of both overall and invasive ipsilateral breast recurrence among members of this patient population.
“Tamoxifen, radiation, or both, as well as the omission of any adjuvant therapy, are all reasonable options. Now, we have more data to help our patients choose among these,” said Dr. Wright in an American Association for Cancer Research press release.
Data from a total of 878 patients were analyzed in the study, drawn from the nonradiation arm of clinical trial NRG/RTOG 9804, in which patients with “good-risk” DCIS were randomly assigned to receive radiotherapy or no radiotherapy, and the “good risk” cohort from trial ECOG-ACRIN E5194, in which outcomes of patients with both higher-risk and “good-risk” DCIS who did not receive radiotherapy were examined. Median follow-up for all patients was 14.9 years. “Good-risk” DCIS was defined as grade 1 or 2, 2.5 cm or smaller, with clear surgical margins of 3 mm or greater.
The investigators reported a statistically significant association between reduced ipsilateral breast recurrence and tamoxifen use (P = .001), estimating 15-year ipsilateral breast recurrence with tamoxifen to be 11.4% and without to be 19.0%. Upon further analysis, the reduction was observed to be significantly associated with tamoxifen use for invasive ipsilateral breast recurrence (P = .0048)—but not for DCIS ipsilateral breast recurrence (P = .089)—and no associations with contralateral breast events were observed. Finally, patients who received tamoxifen were found to be 44% less likely to have any ipsilateral breast recurrence and 51% less likely to have invasive ipsilateral breast recurrence compared with patients who did not receive tamoxifen.
Disclosure: For full disclosures of the study authors, visit sabcs.org.
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