NEW research presented at the San Antonio Breast Cancer Symposium highlights the potential benefits of tamoxifen for patients with “good-risk” ductal carcinoma in situ (DCIS) who forgo radiation therapy (RT) after breast conservation surgery (BCS). Findings from a combined analysis of the NRG Oncology/RTOG 9804 and ECOG-ACRIN E5194 trials show a significant reduction in ipsilateral breast recurrence (IBR) associated with tamoxifen use.
The study evaluated 878 patients, all classified as having “good-risk” DCIS—characterized by a tumor size ≤2.5 cm, grade 1-2, and surgical margins ≥3mm. Among these, 43.1% used tamoxifen, with usage rates higher in NRG/RTOG 9804 (65.6%) compared to ECOG-ACRIN E5194 (30.3%). The median follow-up period was 14.85 years.
Patients who took tamoxifen experienced an estimated 15-year IBR rate of 11.4%, compared to 19.0% for those who did not (p=0.001). The reduction was especially significant for invasive IBR (p=0.0048), though not for DCIS IBR (p=0.089). No association was found between tamoxifen use and contralateral breast events (CBE).
Multivariable analysis confirmed that tamoxifen reduced the risk of any IBR by 44% and invasive IBR by 51%. Other factors, such as tumor size and grade, influenced recurrence risk but did not diminish tamoxifen’s impact. These findings support tamoxifen as an effective adjuvant therapy for reducing recurrence in women with “good-risk” DCIS who opt to skip RT.
Helena Bradbury | AMJ
Reference
Wright JL et al. Impact of Tamoxifen Only after Breast Conservation Surgery for “Good Risk” Duct Carcinoma in Situ: Results from the NRG Oncology/RTOG 9804 and ECOG-ACRIN E5194 Trial. Abstract GS2-02. SABCS, 10-13 December, 2024.
