Breast Cancer Metastasis Masquerading as Primary Colon and G
Breast cancer is the most common malignancy in women worldwide. Despite treatment, recurrence and metastasis are common. Lobular breast cancer most commonly metastasizes to the lungs, liver, lymph nodes, and sites in the brain. Metastasis to the gastrointestinal tract is rare, with few cases reported to date.

Here is a case presented in The American Journal of Case Reports of a 68-year-old female with a history of recurrent invasive lobular breast cancer, positive for estrogen receptor (ER) and progesterone receptor (PR), who underwent bilateral mastectomy, followed by adjuvant chemoradiotherapy and hormonal therapy, presented 27 years later with bone metastasis. She had been treated with anastrozole, letrozole, exemestane, and fulvestrant, and most recently, she was being treated with fulvestrant and palbociclib until year 30, when she presented with progressively worsening nausea, vomiting, abdominal pain, and refractory constipation. Physical examination revealed abdominal distension and tenderness. Evaluation by abdominal x-ray showed proximal large bowel obstruction, but no evidence of pneumoperitoneum. Subsequent gastrografin enema showed a focal, luminal narrowing “apple core” lesion in the sigmoid colon suggestive of primary colon cancer (Figure 1).

A computed tomography (CT) scan of the abdomen confirmed the large bowel obstruction, with a transition point within the distal sigmoid colon. Circumferential narrowing and mucosal thickening were observed at the transition point, thought to be due to an annular carcinoma. The biopsy showed diffuse infiltration and proliferation of neoplastic cells in a sheet-like arrangement within the lamina propria and submucosa consistent with a poorly differentiated adenocarcinoma (Figure 2)

The patient continued to be treated with palbociclib and fulvestrant, which was changed to everolimus and exemestane, and later to oral capecitabine due to the aggressiveness of the disease and the side effects of treatment. During year 32, following treatment with capecitabine, she developed epigastric pain. An upper GI endoscopy revealed a dominant lesion in the gastric body highly suspicious for gastric cancer. Histology was consistent with signet ring carcinoma, a rare variant of lobular carcinoma. IHC testing of the tumor cells were strongly positive for GATA-binding protein 3 (GATA-3), ER and PR, indicating that the stomach tumor was metastasis from breast cancer with signet ring phenotype.

The patient was treated with palliative paclitaxel and gemcitabine chemotherapy. She later developed septic shock with multiorgan failure and died shortly thereafter; 34 years after the initial diagnosis of lobular breast cancer.

Findings in the patient demonstrated how breast cancer metastases to the GI tract can mimic primary GI cancers, especially when the former lesions appear many years after initial cancer diagnosis and treatment. New GI symptoms in patients with a prior history of breast cancer should be thoroughly investigated. In particular, the likelihood of metastases should be evaluated as breast cancer can be clinically and morphologically very heterogeneous.Breast cancer patients should have close follow-up throughout their lifetime, as recurrence and metastatic lesions can present ambiguously even decades later.

Source :