Objective To investigate the relationship between mismatch repair (MMR) protein expression and microsatellite instability (MSI) and tumor TNM staging in colorectal cancer. Methods The clinical data of 1351 patients who underwent radical resection of colorectal cancer at the Xijing Digestive Hospital of Air Force Military Medical University from January 2008 to December 2017 were retrospectively analyzed. The MMR and MSI status in patients with different gender, age and TNM staging were analyzed. Results Of the 1351 specimens, 291 (22％) didn't express MMR protein. Univariate analysis showed that there were significant differences in the deletion rates of MSH2, MSH6 and PMS2 between patients ≥60 years old and<60 years old (all P<0.05);there were significant differences in the deletion rates of MSH2 between stage T3 and the other stages (P<0.05); the deletion rates of MLH1, PMS2 among different N stages, and the deletion rates of MSH2 and MSH6 between stage N0 or N1 and the other N stages were significantly different (all P< 0.05); the deletion rates of PMS2 among different M stages were significantly different (P< 0.05). There were significant differences in PMS2 deletion rates among different TNM stages and MLH1, MSH2 and MSH6 deletion rates between stage Ⅱ or Ⅲ and the other stages (all P< 0.05). There was significant difference in MSI positive rates between patients ≥60 years old and<60 years old (P<0.05); there were significant differences in MSI positive rates between stage T3 or T4 and the other T stages, among different N or M stages, and between TNM stage Ⅱ, ⅢorⅣand the other TNM stages (all P<0.05). Conclusions The MMR protein expression and MSI in colorectal cancer patients are closely related to tumor TNM staging. Detection of MMR protein expression and MSI in colorectal cancer patients has certain reference value for judging TNM staging of colorectal cancer. To a certain extent, it can guide the diagnosis and treatment of patients with colorectal cancer and judge the prognosis.

[Objective] To summarize the clinical manifestations, pathological characteristics, treatment options and prognosis of the world's first case of prostate ductal adenocarcinoma (PDA) complicated with prostate mucinous adenocarcinoma (PMA). [Methods] The clinical and follow-up data of a patient with PDA and PMA treated in Zhongnan Hospital of Wuhan University were retrospectively analyzed, and relevant literature in PubMed and CNKI databases was retrieved. [Results] The patient sought medical attention due to dysuria, frequent urination, urinary urgency and urinary pain for more than half a year, and was admitted to hospital 3 times in total.The initial diagnosis upon the first admission was benign prostatic hyperplasia complicated with prostatic abscess.After 2 months, the patient was readmitted due to worsening symptoms, received transurethral bladder neck incision+ cystoscopy+ transurethral plasma resection of the prostate, and postoperative diagnosis confirmed PDA with local PMA.Three months after surgery, the patient had bleeding.After auxiliary examinations revealed extensive metastasis, he received hormonal therapy.After 9 months, the patient died due to multiple lung metastases. [Conclusion] Early diagnosis has a significant impact on the treatment and prognosis, but there have been no previous reports of PDA combined with PMA, so the lack of specific biomarkers in the early stage has led to missed diagnosis or misdiagnoses.There is no specific treatment for PDA with PMA. Radical prostatectomy was not satisfactory in the treatment of this case.