Although there are some reports[24,25] about the use of mucinous carcinoma neoadjuvant chemotherapy to overcome mucinous carcinoma resistance to chemotherapy and anti-HER2 therapy, the clinical response, reflected by changes in tumor size, was not ideal because the large volume of mucin may lead to the overestimation of tumor size, which refers to the true cancerous component. This evidence concerns the gene MUC5AC and mucinous adenocarcinoma.