Tamoxifen Reduces Breast Cancer Recurrence in Women with DCIS Who Underwent Mastectomy.

BACKGROUND

Adjuvant tamoxifen reduces recurrence in patients with ER-positive DCIS treated with lumpectomy and radiation, but its benefit after mastectomy remains unclear.

METHODS

We retrospectively analyzed 287 patients who underwent mastectomy for pure DCIS at Siriraj Hospital between 2008 and 2017. Recurrence risk factors were assessed using log-rank test, and survival probabilities were estimated with Kaplan-Meier analysis.

RESULTS

Of 180 patients with hormone receptor (HR)-positive pure DCIS treated with mastectomy, 120 (66.7%) received tamoxifen, while the remaining 60 (33.3%) did not. The median follow-up was 8.07 years (0.05-13.8 years). Sixteen (8.9%) recurrences were identified, with 5 in the tamoxifen group and 11 in non-endocrine-therapy (ET) group. The 10-year recurrence-free survival (RFS) was 94.7% in the tamoxifen group compared with 77.9% in the non-ET group. Patients with HR-positive DCIS treated with tamoxifen following mastectomy had significantly less subsequent breast cancer (HR = 0.178; p = 0.001).

CONCLUSIONS

Recurrence of breast cancer after mastectomy for DCIS is rare; however, it carries a high mortality rate for those who relapse. Adjuvant tamoxifen after mastectomy demonstrated a significant reduction in the risk of recurrence in ER-positive DCIS. This study supports the decision to prescribe adjuvant ET in patients with DCIS who underwent mastectomy.