A Rare Cause of Colonic Obstruction: Metastatic Breast Cancer to the Rectum

Abstract

Introduction Breast cancer (BC) is the most prevalent cancer in women and among the leading cause of death in these patients. While BC is known to spread to the bones, lungs, liver, brain, and soft tissues, gastrointestinal (GI) metastasis is rare. Furthermore, metastatic spread specifically to the rectum is exceedingly rare. We present a rare case of a woman with history of breast cancer presenting with rectal metastasis four years after mastectomy. Case Report A 53-year-old woman presented for a colonoscopy following a surveillance abdominal CT scan that showed an incidental thickening of her rectum. There was no history of rectal bleeding. Her past history was significant for grade 2 invasive ductal carcinoma (IDC) of the left breast diagnosed 4 years ago. Immunohistochemical staining was positive for estrogen receptor (ER), progesterone receptor (PR) and negative for human epidermal growth factor receptor 2 (HER2-neu). She was treated with left partial mastectomy, radiation, chemotherapy with Taxotere and cyclophosphamide, and hormonal therapy. She was in remission for approximately 3 years and then found to have recurrence to the bladder when she developed hematuria. At the time of presentation to the colonoscopy, her cancer antigen (CA) 15.3 was 721, CA 125 was 110, and CEA was 23.3. Colonoscopy revealed narrowing at the rectosigmoid with thickened mucosa without a clear obstructive lesion. Even a smaller diameter (11.6 mm) colonoscope could not be passed through the narrow rectosigmoid colon (Image 1). Multiple biopsies showed metastatic carcinoma of primary breast origin (Images 2-3). For her metastatic breast cancer, she was started on various chemotherapy agents including Faslodex and palbociclib and then AZD5363 and olaparib with variable response. Currently she is on Xeloda and has been tolerating it well and does not have any significant obstructive rectal symptoms. Discussion GI metastasis from invasive breast cancer is very rare ( 0.2% for ductal carcinoma and even rarer for lobular carcinoma). Rectal metastasis is even less frequent and only noted in several case reports. This can present masquerading as primary rectal mass, stricture or bleeding, years following the initial diagnosis of breast cancer. As such, physicians should have a heightened suspicion in caring for patients with new anorectal symptoms.1643_A Figure 1 No Caption available.1643_B Figure 2 No Caption available.1643_C Figure 3 No Caption available.