Gastric Metastasis 9 Years Post-mastectomy for Invasive Lobular Carcinoma of the Breast: A Case Report

Introduction Invasive lobular carcinoma (ILC) is the second most common histologic form of breast cancer[1]. Gastric metastasis is rare, found in only 0.3% of gastrectomy specimens[2]. Differentiating between the two is crucial due to differing treatments. This case report details gastric metastasis from primary breast cancer, occurring nine years postmastectomy. Case Presentation A 62-year-old woman with a history of left mastectomy for stage IIA ILC nine years prior presented with dyspepsia. Despite the mentioned surgical intervention, the treatment regimen included adjuvant chemoradiotherapy and hormone therapy. She remained free of disease until the current presentation. Gastroscopy revealed hypertrophic gastritis, stomach ulcers, and biopsies showed a diffuse-type gastric adenocarcinoma. CT imaging revealed stomach thickening with infiltration into surrounding tissues. The patient was treated with the FLOT scheme, followed by subtotal gastrectomy. Histology confirmed gastric metastasis from breast invasive lobular carcinoma. Routine check-ups showed elevated tumor markers, prompting radiological investigation, revealing no distant metastasis. Despite negative findings on abdominal and breast imaging, CT scans indicated disease progression in the stomach. A gastroscopy biopsy confirmed gastric metastasis from ILC. Hormone therapy was started, resulting in significant tumor marker reduction. Discussion Gastric metastases are rare and have nonspecific symptoms; therefore, they are rarely considered in medical practice[2,3]. Moreover, gastric metastasis pathology can mimic primary gastric cancer[4,5]. In this case, as is common in the literature, diffuse-type gastric carcinoma was frequently the preliminary diagnosis from biopsy, with metastatic breast cancer confirmed after subtotal gastrectomy through immunohistochemical analysis[5]. Treatment includes chemotherapy, hormone therapy, or combination therapy, with gastrectomy for limited metastases[6]. Median survival after diagnosis is 10–28 months, with a 2-year survival rate of 23%–53%[7]. Conclusions Breast ILC with gastric metastases is rare and may be mistaken for primary gastric cancer even after 9 years. Diagnosis relies on clinical suspicion, endoscopy and repeated histological examination including immunohistochemistry for appropriate treatment.