Breast Metastasis Of Signet Ring Cell Carcinoma From The Colon: A Case Report

Background: Colon cancer is one of the most common diagnosed malignancies. Although the use of surgery, chemotherapy, radiotherapy, targeted therapy, immunotherapy and other comprehensive treatment, distant metastasis is still one of the main causes for dying of colon cancer. The common metastatic site of colon cancer is liver, lung and bone. In this article, we report a rare case of breast metastasis of signet ring cell carcinoma from the colon. Case Presentation: A 44-year-old woman was diagnosed with colon cancer and received a radical surgery of colon cancer in 2019. Combined with postoperative pathological and CT images, a diagnosis of cT3N2M0 mucinous adenocarcinoma of colon (according to AJCC cancer staging manual, Version 8) was established. Adjuvant chemotherapy (XELOX: oxaliplatin 130 mg/m 2 on day 1 plus capecitabine 1000 mg/m 2 twice daily on days 1 to 14 every 3 weeks for 18 weeks) was performed followed by surgical resection. 14 months later, the patient received mastectomy for breast mass, which was diagnosed pathologically as metastasis of signet ring cell carcinoma from the colon. XELOX chemotherapy regimen (oxaliplatin 130 mg/m 2 on day 1 plus capecitabine 1000 mg/m 2 twice daily on days 1 to 14 every 3 weeks for 24 weeks) combined with bevacizumab (7.5mg/kg on day 1) were used after the mastectomy. The patient was stable disease according to her last examination (RECIST criteria). Conclusion: It is rare to report a patient diagnosed with colon cancer which metastasis to breast. We hope to increase treatment experience for patients with this rare metastasis.