Wu et al found that patients with triple‐negative breast cancer had the lowest CEA level among the four subtypes, whereas Fang et al found elevated cancer antigen 125 (CA125) was more frequently observed in triple‐negative patients compared with other three subtypes and they did not find any difference of serum CEA and CA153 among the four subtypes.6, 7 Thus, the limited knowledge of the relationship between serum tumor markers and the pathological features has obstructed the optimized use of serum tumor markers for patients with breast cancer. This evidence concerns the gene MUC1 and breast cancer.