Hormone Receptor Positive/HER2 Negative Breast Cancer With Isolated Bladder Metastasis: A Rare Case

Abstract

Breast cancer is the most common cancer diagnosed in women in North America. Hormone receptor positive (HR+) and HER2 negative (HER2−) breast cancers account for at least 60% to 70% of all breast cancer cases. They usually metastasize to lymph nodes, bones, liver, lungs, and brain. Urinary bladder is a very unusual site for metastatic HR+/HER2− breast cancer and occurs in only 2% of all metastatic disease. In this article, we present a case of a 63-year-old female with locally advanced breast cancer who underwent mastectomy, adjuvant chemotherapy, radiation, and hormonal therapy. She was in remission for almost 17 years and subsequently presented with hematuria and lower abdominal pain. Cystoscopy was performed, which showed evidence of bladder wall thickening. Histopathology showed metastatic HR+/HER2− breast cancer consistent with her history of breast primary. Imaging studies did not show any other evidence of metastatic disease. She was started on cyclin D kinase 4/6 inhibitor, palbociclib, in combination with an aromatase inhibitor, letrozole. This is an exceedingly rare case of HR+ and HER2− breast cancer with metastasis to the urinary bladder. The late onset of recurrence with bladder metastasis makes this case very unique and to our knowledge only few similar cases have been reported in the literature.

Urinary bladder metastasis from primary breast cancer, a rare and challenging diagnosis. A case report and literature review

“…Four (2.4%) of the 167 included cases with primary breast cancer had UB metastasis. Since then, there had been few reported cases, and was mostly due to local extension [ [8] , [9] , [10] ]. In a retrospective study of 6289 bladder tumors, 282 (4.5%) were characterized as secondary metastases and 7 (2.5%) of them were of primary breast origin; majority (n = 6, 85.7%) were detected only on post-mortem examination [ 5 ].…”

An unusual location for metastasis – Breast cancer in the bladder

“…Prior autopsy studies have shown that breast cancer invades bladders “outside-in”– involving the outer bladder wall with inward invasion through the detrusor muscle. 3 The mucosa is involved last. 2 , 3 Irritative symptoms, including incontinence, and frequency typically arise first and are indicative of detrusor involvement.…”

“… 3 The mucosa is involved last. 2 , 3 Irritative symptoms, including incontinence, and frequency typically arise first and are indicative of detrusor involvement. 2 Involvement of the mucosa, and the associated symptom of hematuria, is often a late finding and explains why cytology is often benign.…”

“…Other case reports of breast cancer metastases to the bladder consider incidence, treatment, and congruity of primary and metastatic immunohistochemistry. 2 , 3 , 4 Our case is one of incongruent primary and metastatic immunohistochemistry and our discussion focuses on detection and consideration from the field of urology, rather than oncological management.…”

“…In total, 55 incidents of breast cancer metastases to the bladder have been reported, most found post-mortem. 2 , 3 We present the case of a 64-year-old woman status post simple mastectomy with node-negative ER+/PR+/HER2-breast cancer who underwent adjuvant chemotherapy and completed 10 years of aromatase inhibition for a total cancer-free period of 13 years prior to diagnosis with metastatic disease to the bladder.…”