Metastasizing to the colon from triple-negative breast cancer: A case report and review of literature

Table 1 The timeline of the patient’s clinical history

Timeline	Diagnosis and treatment process	Result
July 2020	Ultrasound-guided puncture biopsy and pathological examination	Diagnosed with triple-negative breast cancer
Until October 2020	Six cycles of preoperative neoadjuvant chemotherapy	Significant shrinkage of the breast mass and supraclavicular area; no apparent reduction in size for the axillary lymph nodes
November 2020	A modified radical mastectomy procedure	Postoperative pathology: Invasive ductal carcinoma, 45 of 46 examined axillary lymph nodes (+), gross cystic disease fluid protein 15 (+), GATA-binding protein 3 (+), E-cadherin (+), CK7 (+), S-100 (+), and ki-67 (10%); estrogen receptor, human epidermal growth factor receptor 2 (-), progesterone receptor (-) and CK14 (-)
November 2020 to November 2021	Chemotherapy consisting of capecitabine and radiotherapy	CEA 4.3 ng/mL and CA 19-9 25.1 U/mL
February 2021 to December 2021	Follow-up	No observed elevation in CEA and CA 19-9 tumor markers, and no evidence of metastatic disease with positron emission tomography/CT
February 2022	Colonoscopy, laboratory investigations, CT scan and biopsy outcomes	A comprehensive preoperative diagnosis with ascending colon cancer
February 2022	Laparoscopic radical right hemicolectomy, morphological and immunohistochemical examination	Diagnosed with colonic metastasis from breast cancer

CA: Cancer antigen; CEA: Carcinoembryonic antigen; CK: Cytokeratin; CT: Computed tomography.