However, this does not mean that determination of MMR status is useful in all cancers; although MMR deficiency is common in colorectal, gastric, and endometrial cancer, it is less commonly seen in other cancers such as breast cancer and sarcoma and has never been reported in many cancers including acute myeloid leukaemia and nasopharyngeal carcinoma [14]. This evidence concerns the gene MRC1 and cancer.