Aggressive recurrence of early breast invasive ductal carcinoma with gastric metastasis during adjuvant hormonal therapy

Abstract

Introduction: Gastric metastasis of breast invasive ductal carcinoma is rare. We present a case of a patient developing aggressive recurrence of early breast invasive ductal carcinoma with gastric metastasis in the third year of adjuvant hormonal therapy. A rarely observed increase in human epidermal growth factor receptor 2 (HER2) overexpression was also observed at the recurrent metastatic sites, and this situation strongly influenced therapeutic management. Case presentation: A 49-year-old Japanese female with prolonged back pain was examined by abdominal ultrasound to eliminate the possibility of abdominal malignancy; she was found to have multiple tumors in the liver. Contrast-enhanced computed tomographic (CT) imaging was performed for thorough examination, revealing multiple tumors in abdominal lymph nodes and in the lungs in addition to the liver. An integrated positron emission tomographic CT scan showed metabolically active foci distributed throughout the body, including the thoracic and lumbar vertebrae, para-aortic lymph nodes, liver, and stomach. At the age of 46, the patient had undergone a lumpectomy without axillary lymph node dissection for early breast invasive ductal carcinoma (pT1N0M0 Stage I), and the cancer was positive for both estrogen and progesterone receptors while not overexpressing HER2. Currently, however, biopsies from gastric and liver tumors showed adenocarcinoma with histological and immunohistochemical properties similar to those of the previous breast invasive ductal carcinoma, indicating metastatic breast cancer. Interestingly, HER2 was overexpressed in the metastatic foci, and the difference in expression status influenced the choice of treatment. Conclusions: Aggressive recurrence of early breast invasive ductal carcinoma with gastric metastasis is rare. Furthermore, HER2 expression status differed between primary and metastatic foci, and reassessment of expression status was helpful for informing decisions on optimal treatment strategy.