Metastasis to the bladder from primary breast cancer: A case report and literature review.

Breast cancer is the most prevalent malignant tumor affecting women and represents the leading cause of female cancer-related mortality worldwide. Although distant organ metastasis accounts for the majority of breast cancer-related deaths, reports on bladder metastasis are limited in the existing literature. The present study describes the case of a patient with bladder metastasis originating from breast cancer. In addition, the present study also provides a review of 54 cases of similar disease that have been documented in the currently available literature. The literature review aims to elucidate the clinicopathological characteristics and therapeutic approaches for such conditions. The median time from breast cancer diagnosis to bladder metastasis was found to be 5.6 years (range, 0-28 years). The origin of the bladder metastases was predominantly invasive ductal carcinoma (IDC) accounting for 52.3% of cases, followed by invasive lobular carcinoma, accounting for 40.9% of cases. The pathology in the primary tumor was the same as the pathology of the bladder metastases in all cases. There was an 88.9% concordance rate for estrogen receptor status, while the progesterone receptor status was 83.3% and the human epidermal growth factor receptor 2 expression status was 100%. The primary initial symptoms included urinary system manifestations, such as increased frequency, urgency, dysuria, urinary incontinence, nocturia and gross hematuria. For the cystoscopic examination, the predominant findings were bladder wall thickening or masses, along with ureteral orifice masses. Overall, the present study demonstrated that the occurrence of bladder metastasis often follows the metastasis of other organs, with IDC being the most prevalent subtype. The pathological characteristics between the primary tumor and bladder metastasis exhibit a high degree of concordance.