Ascending colon metastasis after breast cancer surgery: a case report and literature review.

Background: Breast cancer is the most common cancer in women. The tumor is prone to metastasize in the brain, lung, liver, bone, and other organs; however, generally, it is less likely to metastasize in the digestive tract. Thus, breast cancer metastasizes to colon is rarely happened and easily ignored by clinicians. Such misdiagnosis may lead to delay the further diagnosis and treatment of patients, or even cause the life danger of patients due to the progress of the disease. Therefore, we propose such case reports to arouse clinicians' attention to the rare case of digestive tract metastasis after treatment of breast cancer. We also conducted a retrospective analysis of the relevant case reports. We suggest that because breast cancer with gastrointestinal metastasis rarely occurs, and because of the lack of specificity of syndromes, it is easily misdiagnosed. Thus, the attention of the receiving doctor needs to be drawn to this tumor. We also summarized the specificity and sensitivity of the commonly used immunohistochemical detection indicators of digestive tract metastasis of breast cancer. Case Description: We presented a 67-year-old female went to hospital because of "acute pain in the right lower abdomen", after computed tomography (CT) examination, the patient was diagnosed as "acute appendicitis" and underwent laparoscopic appendectomy (LA), the post-surgery pathology confirmed metastatic carcinoma to the appendix from the breast that was removed 10 years early. The patient first came to our hospital 10 years ago because of the right breast malignant tumor. After modified radical mastectomy for right breast cancer, the patient underwent chemotherapy for 6 cycles. Tamoxifen endocrine therapy was administered after chemotherapy. The patient had a regular follow-up, with no signs of distant metastasis and local recurrence. Conclusions: Metastasis from breast cancer to the gastrointestinal tract is extremely rare. For patients with breast cancer, endoscopy should be adopted as a routine follow-up item. For suspicious lesions found under endoscopy, immunohistochemistry stain should be adopted to ensure the diagnosis. For lesions that are confirmed to be metastatic from breast cancer, proper treatment should be carried out based on patients' condition to improve the prognosis.