Micro-metastases into the uterine leiomyoma from invasive ductal breast cancer under adjuvant tamoxifen therapy: case report.

Metastasis of breast cancer to the uterus is extremely rare. However, breast cancer is the leading tumor metastasizing from extragenital organs to the uterus. The most common signs of uterine metastasis are bleeding and mass effect. Tamoxifen use is known to increase risk of endometrial cancer. Immunohistochemical staining with GCDFP can be useful in differentiating primary uterine tumors from breast cancer metastasis. Metastasis to the uterus has been reported to worsen the prognosis. Although hysterectomy has been effective on survival, treatment modality to be used in the presence of other systemic metastases is not clear. Locoregional treatments can be used in oligometastatic cases. In addition, removal of solitary organ metastasis together with bone metastasis provides improvement in survival.