Two Cases of Distant Metastasis After Mastectomy for Breast Ductal Carcinoma In Situ.

While the prognosis for ductal carcinoma in situ (DCIS) of the breast is generally excellent, distant metastasis after appropriate local treatment is extremely rare. We experienced two cases of distant metastasis after mastectomy for breast ductal carcinoma in situ. In both cases, the surgical margins were negative, the sentinel nodes were negative for metastasis. The first case was a 67-year-old woman who developed lung metastases four years after mastectomy for high-grade DCIS. The second case was a 34-year-old woman with intermediate-grade DCIS who developed intraductal recurrence localized to the nipple two years after the initial nipple-sparing mastectomy and multiple lung and liver metastases six months later. Both cases developed distant metastases despite appropriate local treatment, without preceding or concurrent invasive local recurrence. Although the probability of distant recurrence is low, it is important to inform patients about the risk of recurrence.