Gastric cancer metastases to the breast: systemic review and meta-analysis of the English literature

INTRODUCTION: Gastric cancer (GC) metastasis to the breast is extremely rare. We report a case of a female patient with primary gastric carcinoma with breast metastasis and conduct an analysis and review of the English literature. EVIDENCE ACQUISITION: Literature databases including "ScienceDirect," "Springer," "PubMed" and "google scholar," were extensively searched up to 2021, using relevant keywords, such as: 'Stomach or gastric', 'tumor or cancer or carcinoma', 'breast or mammary' and "metastases". All the studies were reviewed, and the following information was extracted: gender, age, clinical presentation, histological type, time to breast metastasis, other sites of metastasis, management protocols, and survival. Only English studies were included. EVIDENCE SYNTHESIS: Atotal of 91 cases were eligible for the analysis. Of these, 74 (81.3%) were females, of whom were 4 pregnant. The mean age was 43.91. The most common histological subtype was Signet ring cell adenocarcinoma (SRCC) (48.35%). The most common tumor markers in cases of primary gastric cancer with breast metastasis were CK20, CK7, CEA, and CDX2. Mean survival was almost 6.6 months. CONCLUSIONS: GC metastasis to the breast is an uncommon event with a poor prognosis. Clinical history, diagnostic imaging, and anatomopathological and immunohistochemical examinations are important to distinguish metastatic cancer from primary breast cancer, allowing patients to receive appropriate treatment.