Lung cancer is the most common cancer in China and even in the world, and it is also the main cause of cancer death. Patients with anaplastic lymphoma kinase (ALK) gene alterations have the opportunity to receive molecularly targeted therapies. The inhibitors of anaplastic lymphoma kinase, such as ALK-tyrosine kinase inhibitors (ALK-TKIs) significantly prolong the survival of patients. ALK gene variant types include point mutation, amplification, fusion/rearrangement, and ALK fusion is more common than other types. However, the effect of different types of gene changes in molecular targeted therapy is different. Therefore, this paper introduced the relevant contents of different variants of ALK gene, focused on the research progress of targeted therapy, and proposed the future development direction.
.

Lung cancer represents the main cause of cancer-related deaths worldwide, and non-small cell lung cancer (NSCLC) is the most main subtype. More than half of NSCLC patients have already developed distant metastasis (DM) at the time of diagnosis and have a poor prognosis. Therefore, it is necessary to find new biomarkers for predicting NSCLC DM in order to guide subsequent treatment and thus improve the prognosis of NSCLC patients. Numerous studies have shown that microRNAs (miRNAs) are abnormally expressed in lung cancer tissues and play an important role in tumorigenesis and progression. The aim of this study is to identify differentially expressed miRNAs in lung adenocarcinoma tissues with DM group compared to those with non-distant metastasis (NDM) group, and to construct a miRNA signature for predicting DM of lung adenocarcinoma.

One of the most important treatment modalities for non-small cell lung cancer (NSCLC) is immune checkpoint inhibitor. Nevertheless, a small percentage of patients do not respond well to these therapies, highlighting the significance of identifying important CD8+ T cell subsets for immunotherapy and creating trustworthy biomarkers. The purpose of this study is to assess the potential utility of TIM3+CD8+ T cells as new biomarkers by examining their expressions in various areas of the NSCLC tumor microenvironment.

Numerous researches indicated that electromagnetic pulses (EMP) possessed advantages such as strong targeting, minimal side-effects and low treatment cost in tumor therapy, but its optimum parameters for treatment and the relationship between EMP and tumor-derived exosomes remains unclear. This study aims to clarify the effects of EMP with different parameters on the quantity and miRNA (microRNA) of exosomes secreted by human non-small cell lung cancer A549 cells, providing beneficial reference for the clinical application of EMP and related research.

Objective: Using methylation characteristics of human genes to construct machine learning predictive models for screening cervical cancer and precancerous lesions. Methods: Human DNA methylation detection was performed on 224 cervical exfoliated cell specimens from the Cancer Hospital of the Chinese Academy of Medical Sciences, Tianjin Central Hospital of Gynecology Obstetrics, Xinmi Maternal and Child Health Hospital of Henan Province, West China Second Affiliated Hospital of Sichuan University, and Heping Hospital Affiliated to Changzhi Medical College collected during April 2014 and March 2015. The hypermethylated gene fragments related to cervical cancer were selected by high-density, high-association, and hypermethylated gene fragment screening and the LASSO regression algorithm. Taking cervical intraepithelial neoplasia grade 2 (CIN2) or more severe lesions as the research outcome, machine learning predictive models based on the random forest (RF), naive Bayes (NB), and support vector machine (SVM) algorithm, respectively, were constructed. A total of 144 outpatient specimens were used as the training set and 80 cervical exfoliated cell specimens from women participating in the cervical cancer screening program were used as the test set to verify the predictive models. Using histological diagnosis results as the gold standard, the detection efficacy for CIN2 or more severe lesions of the three machine learning predictive models were compared with that of the human papilloma virus (HPV) detection and cytological diagnosis. Results: In the training set of 144 cases, there were 34 cases of HPV positivity, with a positive rate of 23.61%. Cytologically, there were 37 cases diagnosed as no intraepithelial lesion or malignancy (NILM), and 107 cases diagnosed as atypical squamous cells of undetermined significance (ASC-US) or above. Histologically, there were 28 cases without cervical intraepithelial neoplasia or benign cervical lesions, 31 cases of CIN1, 18 cases of CIN2, 31 cases of CIN3, and 36 cases of squamous cell carcinoma. Seven hypermethylated gene fragments were selected from 45 genes, and three machine learning prediction models based on the RF, NB, and SVM algorithm, respectively, were constructed. In the validation set of 80 cases, there were 28 cases of HPV positivity, with a positive rate of 35.00%. Cytologically, there were 65 cases diagnosed as NILM and 15 cases as ASC-US or above. Histologically, there were 39 cases without cervical intraepithelial neoplasia or benign cervical lesions, 10 cases of CIN1, 10 cases of CIN2, 11 cases of CIN3, and 10 cases of squamous cell carcinoma. In the validation set, the area under the curve (AUC) values of the RF model, NB model, SVM model, HPV detection, and cytological diagnosis of CIN2 or above were 0.90, 0.88, 0.82, 0.68, and 0.45, respectively. The DeLong test showed that there was no statistically significant difference in the AUC values between the RF, NB, and SVM models (all P＞0.05), and the AUC values of the RF and NB models were higher than that of HPV detection (both P＜0.01), and the AUC values of the RF, NB, and SVM models were higher than that of cytological diagnosis (all P＜0.01). Compared with the NB model, the sensitivity of the RF model was similar (80.65% vs. 77.42%), but the specificity of the NB model was much higher than that of the RF model (93.88% vs. 73.47%). Conclusion: Among the machine learning prediction models for cervical cancer and precancerous lesions constructed based on human DNA methylation, the NB model has good predictive performance for CIN2 and above lesions, and may be used for screening of cervical cancer and precancerous lesions.

Objective: To explore the effects and potential mechanisms of chemokine-like factor-like MARVEL transmembrane domain-containing Protein 3 (CMTM3) on the proliferation and migration of glioblastoma (GBM) cells. Methods: Using CMTM3 expression data from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) databases, we analyzed the differential expression of CMTM3 in GBM tissues and its impact on the prognosis of GBM patients. Immunohistochemical staining and protein content determination of CMTM3 was performed on GBM and adjacent non-cancerous tissue samples from 11 GBM patients who underwent surgical treatment at the Affiliated Hospital of Guizhou Medical University between November 3, 2022 and March 15, 2023. Additionally, the expression of CMTM3 was validated in GBM cell lines U87, U251, LN229, and the human astrocyte (NHA) cell line using real-time quantitative polymerase chain reaction (RT-qPCR) and Western blot analyses. Stable cell lines with silenced and overexpressed CMTM3 (sh-CMTM3 group and OE-CMTM3 group) were constructed using U251 cells. The effect of CMTM3 expression on cell proliferation was assessed using the Cell Counting Kit-8 (CCK-8) assay. Flow cytometry was employed to examine the impact of CMTM3 expression on the cell cycle. Transwell assays were conducted to evaluate the influence of CMTM3 expression on cell migration. Bioinformatics analysis, Western blotting, NF-κB activation-nuclear translocation assays, and the NF-κB pathway inhibitor pyrrolidine dithiocarbamate ammonium (PDTC) were used to validate the effect of CMTM3 on the NF-κB pathway. Finally, a subcutaneous tumorigenesis assay in nude mice was performed to observe the impact of CMTM3 expression on the in vivo growth of U251 cells. Results: Bioinformatics analysis revealed that CMTM3 is highly expressed in GBM tissues. Patients with a high CMTM3 expression had lower overall survival (OS) and disease-free survival (DFS) rates compared with those with a low CMTM3 expression (with P values of 0.010 and 0.032, respectively). Among the 11 GBM pathological specimens, 10 samples exhibited higher CMTM3 protein expression levels in the cancerous tissue compared with the adjacent non-cancerous tissue. The average CMTM3 protein expression in these samples was 0.44±0.09, significantly higher than that in the adjacent non-cancerous tissues (0.12±0.02, P＜0.001). In one sample, the difference in CMTM3 protein expression between the cancerous and adjacent non-cancerous tissues was not statistically significant (P=0.750).The RT-qPCR results showed that the mRNA expression level of CMTM3 in NHA cells was 1.0±0.1, whereas in GBM cells U87, LN229, and U251, the levels were 2.1±0.3, 3.4±0.5, and 3.7±0.8, respectively, all significantly higher than that in NHA cells (all P＜0.01). Western blot results demonstrated that the protein expression levels of CMTM3 in GBM cells U87, LN229, and U251 were 1.5±0.2, 1.8±0.2, and 1.9±0.1, respectively, also higher than that in NHA cells (0.7±0.2, all P＜0.01), with the highest level observed in U251 cells. The CCK-8 assay, Flow cytometry, and Transwell migration experiments indicated that cell viability was inhibited in the sh-CMTM3 group, with an increase in the proportion of cells in the G0/G1 phase (P＜0.01) and a decrease in the S phase (P＜0.01), and the number of migrated cells was 233.6±35.5, lower than that in the sh-NC group (P＜0.001). Conversely, the OE-CMTM3 group showed enhanced cell viability, a reduction in the proportion of cells in the G0/G1 phase (P＜0.01), and an increase in the S phase (P＜0.01), and the number of migrated cells was 1212.0±20.8, higher than that in the OE-NC group (P＜0.001). However, in the OE-CMTM3+PDTC group, cell viability, cell cycle distribution (G1, S, and G2 phases), and cell migration numbers showed no significant changes (all P＞0.05). Western blot analysis and NF-κB activation-nuclear translocation assay results indicated that in the sh-CMTM3 group, the p-p65/p65 ratio was 0.51±0.04 and the p-IκBα/IκBα ratio was 0.39±0.03, both lower than those in the sh-NC group (both P＜0.01). The cytoplasmic staining rate was (49.29±1.98)%, higher than that in the sh-NC group (P＜0.01). In the OE-CMTM3 group, the p-p65/p65 ratio was 2.27±0.10 and the p-IκBα/IκBα ratio was 2.14±0.15, both higher than those in the OE-NC group (both P＜0.01). The cytoplasmic staining rate was (18.96±1.44)%, lower than that in the OE-NC group (P＜0.01). In the OE-CMTM3+PDTC group, there were no significant differences in the p-p65/p65 ratio, p-IκBα/IκBα ratio, and cytoplasmic staining rate compared with the OE-NC group (all P＞0.05). The subcutaneous tumorigenesis assay in nude mice showed that the tumor volume in the sh-CMTM3 group was (408.9±96.2) mm³, smaller than that in the sh-NC group (P=0.003). The tumor volume in the OE-CMTM3 group was (1 514.5±251.5) mm³, larger than that in the OE-NC group (P=0.005). Conclusions: In GBM, CMTM3 is highly expressed and negatively correlated with both OS and DFS of patients. CMTM3 regulates the proliferation and migration abilities of U251 cells through the NF-κB signaling pathway.

Based on the epidermal growth factor receptor(EGFR)/mitogen-activated protein kinase(MAPK) signaling pathway-mediated cell proliferation, this study explores the effect of cisplatin combined with Guiqi Yiyuan Ointment on Lewis lung cancer-bearing mice. A total of 60 male C57BL/6 mice were randomly divided into a blank group with 10 mice and a modeling group with 50 mice. After modeling, they were randomly divided into the model group, cisplatin group, and low-, medium-, and high-dose groups of cisplatin combined with Guiqi Yiyuan Ointment, with 10 mice in each group. After 14 days of medication, the general condition of the mice was observed; body weight was measured, and organ index and tumor inhibition rate were calculated. Hematoxylin-eosin(HE) staining was used to observe the pathological morphology changes in tumor tissue. Immunohistochemistry was used to detect the positive rate of Ki-67 antigen(Ki-67) and proliferating cell nuclear antigen(PCNA) in tumor tissue. Western blot and real time-quantitative polymerase chain reaction(qPCR) were used to detect the expression of related proteins and mRNA in tumor tissue. Flow cytometry was used to detect the cell cycle of tumor cells in tumor tissue. The results showed that compared with that in the blank group, the general condition of mice in the model group deteriorated; the body weight, as well as thymus and spleen index of mice in the model group decreased after 14 days of medication. Compared with that in the model group, the general condition of mice in the cisplatin group deteriorated, while the condition of mice in the combined groups improved; the body weight, as well as thymus and spleen index of mice in the cisplatin group decreased, while the three indicators in the combined groups increased; the tumor weight of each medication group decreased, and the tumor inhibition rate increased; there were varying degrees of necrosis in tumor cells of each medication group, and the tightness of tumor cells, the increase in the number of cell nuclei and chromatin, and mitosis all decreased. The positive rate of Ki-67 and PCNA, as well as the protein expression and ratio of p-EGFR/EGFR, rat sarcoma viral oncogene homolog(Ras), phosphorylated Raf-1 protein kinase(p-Raf-1)/Raf-1, phosphorylated mitogen-activated protein kinase kinase(p-MEK)/MEK, phosphorylated extracellular signal-regulated kinase(p-ERK)/ERK and the mRNA expression of EGFR, Ras, Raf-1, MEK, and ERK all decreased. The proportion of tumor cells in the G_0/G_1 phase of each medication group increased, and that in the S phase decreased. In addition, there was no significant difference in the G_2/M phase. Compared with that of the cisplatin group, the tumor weight of the combined groups decreased, and the tumor inhibition rate increased. The necrosis and mitosis of tumor cells in the combined groups were more pronounced; the positive rate of Ki-67 and PCNA, the protein expression and ratio of p-EGFR/EGFR, Ras, p-Raf-1/Raf-1, p-MEK/MEK, and p-ERK/ERK, as well as the mRNA expression of EGFR, Ras, Raf-1, MEK, and ERK in the combined groups all decreased. The proportion of tumor cells in the G_0/G_1 phase of the combined medium-and high-dose groups increased, and that in the S phase decreased. There was no significant difference in the proportion of tumor cells of the combined groups in the G_2/M phase. This indicates that the combination of cisplatin and Guiqi Yiyuan Ointment can enhance the anti-tumor effect of cisplatin on tumor-bearing mice, and the mechanism may be associated with the inhibition of the EGFR/MAPK pathway, which accelerates the arrest of tumor cells in the G_0/G_1 phase, thereby inhibiting the proliferation of tumor cells. At the same time, the study also indicates that Guiqi Yiyuan Ointment may reduce the damage of tumors to mice and the toxic side effects brought by cisplatin chemotherapy.

Objective: To investigate the impact of SMARCA4 mutations on the outcomes of patients with advanced lung adenocarcinoma with epidermal growth factor receptor (EGFR) mutations. Methods: In the Memorial Sloan Kettering Cancer Center (MSK) MetTropism study, 960 patients with advanced EGFR-mutated lung adenocarcinoma were screened and included in the MSK cohort, composing of 313 males and 647 females, with a median [M(Q1, Q3)] age of 64 (56, 72) years. A retrospective analysis was conducted on the data of 178 patients with advanced EGFR-mutated lung adenocarcinoma who received EGFR tyrosine kinase inhibitors (TKIs) treatment in the Department of Oncology, the First Affiliated Hospital of Nanjing Medical University, from January 2018 to December 2022. Among these patients, 69 were males and 109 were females, with a median age of 63 (54, 69) years. The follow-up of patients from the First Affiliated Hospital of Nanjing Medical University was conducted up to December 31, 2023, with a median follow-up time of 26.6 (95%CI: 24.6-28.6) months for the entire cohort, and 29 patients were lost to follow-up. Survival curves were plotted using the Kaplan-Meier method, and the log-rank test was used to compare the relationship between SMARCA4 gene alternations and prognosis. Results: In the 960 patients of the MSK cohort with advanced EGFR-mutated lung adenocarcinoma, the SMARCA4 gene alternations rate was 4.2% (40/960). The median overall survival (OS) for patients without SMARCA4 gene alternations was 41.5 (95%CI: 35.6-47.3) months, which was superior to that of patients with SMARCA4 gene alternations [15.6 (95%CI: 7.9-23.4) months, P<0.001]. Patients with SMARCA4 gene alternations had a higher risk of mortality, with an HR (95%CI) of 1.97 (1.35 to 2.88). Among the 178 patients with advanced EGFR-mutated lung adenocarcinoma from the First Affiliated Hospital of Nanjing Medical University, the SMARCA4 gene alternations rate was 4.5% (8/178). The median progression-free survival (PFS) for patients without SMARCA4 gene alternations was 16.1 (95%CI: 12.2-20.0) months, which was superior to the median PFS of patients with SMARCA4 gene alternations [6.0 (95%CI: 1.3-10.7) months, P<0.001]. The median OS for patients without SMARCA4 gene alternations was 50.1 (95%CI: 28.1-72.1) months, which was also superior to the median OS of patients with SMARCA4 gene alternations [17.6 (95%CI: 15.4-19.8) months, P=0.001]. Conclusion: SMARCA4 alternation is an important factor associated with poor prognosis in patients with advanced EGFR-mutant lung adenocarcinoma.

Objective: To investigate the clinicopathological and genetic features of infantile rhabdomyofibrosarcoma (IRFS) with EGFR kinase domain duplication (EGFR-KDD). Methods: The clinical, morphological and immunohistochemical features of three IRFS with EGFR-KDD diagnosed from January 2022 to January 2024 at Department of Pathology, Foshan Traditional Chinese Medicine Hospital, Foshan, China were retrospectively analyzed using PCR or next generation sequencing technique; and related literature was reviewed. Results: There were 1 male and 2 females, aged at presentation ranging from 1 to 4 years. The tumor occurred in the left thigh, right maxillofacial region, and right popliteal space. The presenting symptom was a painless mass which was accidentally discovered. The maximum diameter of tumors ranged from 3 to 5 cm. Microscopically, the tumors were poorly defined and composed of relatively monomorphic spindle cells, arranged in diffuse, fascicular growth patterns, with moderate pale eosinophilic cytoplasm. Mitoses were abundant. A few round rhabdomyoblastic tumor cells with abundant eosinophilic cytoplasm were found. There was no evidence of hemorrhage or necrosis. The tumor cells expressed vimentin, SMA, MSA, desmin, MyoD1 and myogenin; and the Ki-67 proliferation index was 10%-60%. RT-PCR showed EGFR-KDD in all three cases. Gene fusion was detected in three cases based on next generation sequencing, but only one case had EGFR-KDD. Follow-up data for 12 to 36 months showed two patients died of the disease and one patient was alive without recurrences and metastasis. Conclusions: IRFS is a rare soft tissue tumor that resembles infantile fibrosarcoma but has immunohistochemical evidence of rhabdomyoblastic differentiation. It more commonly occurs in infants and tends to appear in limbs and torso with poor prognosis. Aggressive multimodality treatment is recommended for these patients. EGFR-KDD may be a genetic driver to IRFS. Clinical response to EGFR targeted therapy might be promising in the future.

Objective: To investigate the clinicopathological characteristics of solid, endometrial-like and transitional (SET) cell growth subtype in high-grade serous ovarian carcinoma (HGSC). Methods: Clinical data of 25 cases of HGSC-SET were collected from January 2020 to March 2024 at the Affiliated Suzhou Hospital of Nanjing Medical University, and their histological features were analyzed. Immunohistochemical stains were used to analyze the expression of ER, PR, PAX8, WT-1, p16, p53 and Ki-67. Next generation sequencing method was used to detect breast cancer susceptibility (BRCA1/2) gene mutation, homologous recombination deficiency (HRD) status, and other homologous recombination repair (HRR) genes. The difference of HRD status between HGSC-SET and typical HGSC patients was further compared. Results: The age of HGSC-SET patients ranged from 41 to 81 years, with an average age of 59 years and a median age of 57 years. Four cases were premenopausal and 21 were postmenopausal. There were 12 cases of bilateral ovarian masses and 13 cases of unilateral ovarian masses. Serum CA125 was elevated in 21 patients and CA19-9 in 2 patients. Lymph node involvement was found in 9 cases, and distant dissemination or metastasis was found in 15 cases. Tumor cells were found in ascites of 10 cases. All the cases were of mixed type, with both typical components (papillae, micropapillae, and glands) and SET components. The total proportion of SET components was>25%. There were 15 cases with comedo/map-like necrosis. Most of the SET form showed pushing pattern of invasion, while the classic form showed infiltrative pattern of invasion. All 25 cases of HGSC-SET showed mutant type staining of p53, of which 20 cases indicated missense mutation and 5 cases indicated nonsense mutation. The positive rates of PAX8, WT-1 and p16 were 100% (25/25), 84% (21/25) and 92% (23/25), respectively. The positive rate of ER was 80% (20/25) in the SET morphological region and 68% (17/25) in the classic morphological region. The positive rate of PR was 16% (4/25) in the SET morphological region and 32% (8/25) in the classic morphological region. The proliferative index of Ki-67 was 60%-95% in the SET region and 20%-90% in the classic region. BRCA1/2 gene mutation was detected in 36% (9/25) of HGSC-SET patients. Among them, 2 cases had BRCA1 gene mutation, 6 cases had BRCA2 gene mutation, and 1 case had gene mutation both in BRCA1 and BRCA2. HRD was positive in 84% (21/25) of patients and negative in 16% (4/25) of patients. The positive rate of HRD in BRCA1/2 wild-type cases was 12/16. A total of 21 patients had HRR-related gene alterations other than BRCA1/2. The mutation rate of BRCA1/2 gene in HGSC-classic patients was 4/20, and the positive rate of HRD was 11/20. Conclusions: Histologically, HGSC-SET presents as a mixed pattern, with comedo/map-like necrosis in most cases. The mutation rate of BRCA1/2 and the positive rate of HRD are higher in HGSC-SET than in HGSC-classic type. BRCA1/2 wild-type HGSC-SET also has a higher HRD positive rate. Besides BRCA1/2, other HRR related gene mutations should not be ignored to avoid missing patients who may benefit from PARP inhibitor treatment.

Objective: To investigate the expression pattern of pan-TRK protein in colorectal cancers with NTRK gene fusion and mismatch repair deficient (dMMR) and to analyze its molecular pathological characteristics. Methods: A total of 117 dMMR colorectal cancers diagnosed in the Department of Pathology of Henan Provincial People's Hospital, Zhengzhou, China from 2020 to 2023 were collected. Immunohistochemistry (IHC), fluorescence in situ hybridization (FISH) and DNA/RNA-based next-generation sequencing (NGS) were used to detect pan-TRK protein expression and fusion partner genes in tumors, and to further explore the correlation between pan-TRK staining patterns and partner genes. Results: IHC and FISH were performed successfully in formalin-fixed paraffin-embedded tissues from 117 dMMR colorectal cancer patients. There were 15 (15/117, 12.8%) cases with positive pan-TRK, including 6 cases with strong staining in tumor cell membrane and cytoplasm, 2 cases with weakly granular staining in tumor cytoplasm, 2 cases with moderate dot-like staining in near 5% tumor cell nuclei, 1 case with moderately to strongly granular staining in the cytoplasm and membrane of tumor cells, 1 case with moderately to weakly granular staining in about 60% of the tumor cells, 1 case with strongly staining in about 1% of the tumor cells, 1 case with moderately to strongly staining in about 3% of the tumor cells and 1 case with diffuse, moderate para-nuclear dot-like and weakly perinuclear granular staining. NTRK1 gene disruption was detected in 6 cases (6/117, 5.1%) and consistent with diffusely strong expression of pan-TRK. Based on DNA/RNA NGS, it was further confirmed that the 6 cases with NTRK1 gene disruption all carried TPM3-NTRK1 fusion gene, and all had high microsatellite instability and high tumor mutation burden. No KRAS, NRAS, BRAF V600E or TP53 gene mutations were detected. Four patients carried frame shift mutations in RNF43. Other molecular changes included 3 cases with ROS1 gene mutation, 2 cases with BRAC, ALK, and EGFR gene mutations, 2 cases with ATM gene mutation, and 2 cases with KIT gene mutation. These were missense/frame shift mutations that were associated with no clinical significance. The nine pan-TRK-positive cases without NTRK gene fusion detected with DNA-based NGS were further confirmed with RNA-based NGS, and no NTRK gene fusion was found. The sensitivity and specificity of NTRK gene fusion detected using IHC were 100.0% and 92.5%, respectively. The sensitivity and specificity of diffusely strong membranous/cytoplasmic staining were both 100.0%. Conclusions: Pan-TRK protein has various expression patterns in dMMR colorectal cancer. Its diffusely strong expression is highly suggestive of NTRK1 gene fusion. TPM3-NTRK1 gene fusion is a common form of NTRK gene fusion in dMMR colorectal cancer.

Objective: To investigate whether the immunohistochemical results of two markers PMS2 and MSH6 (2-MMR) could replace the four markers MLH1, PMS2, MSH2 and MSH6 (4-MMR) to detect mismatch repair deficient (dMMR) cancers. Methods: A retrospective analysis was conducted with summary of immunohistochemical data from 7 867 cases of gastric cancer, colorectal cancer, endometrial cancer, and other diseases in the Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China, from March 2018 to March 2023. The consistency of 2-MMR and 4-MMR results was examined. Microsatellite instability (MSI) and next-generation sequencing (NGS) were performed in patients with specific phenotypes. Results: The Cohen κ values of 2-MMR and 4-MMR in gastric cancer, colorectal cancer, endometrial cancer and other diseases were 0.88, 0.99, 0.88 and 1.00, respectively. The overall consistency, sensitivity and specificity were 0.97, 99.6%, and 100.0%, respectively. Both 2-MMR and 4-MMR could detect the difference between various clinicopathological features. 24 (0.3%) of the 7 867 patients were found to have a special phenotype of MMR, and 6 of them were selected for MSI and NGS molecular testing. MSI analysis showed MSI-H in all cases, while NGS found that 5 of them had MMR-related gene mutations and 1 had POLE p.S297F mutation. Conclusions: Compared with 4-MMR, 2-MMR has high consistency, specificity and sensitivity. The cases with special phenotype only account for extremely low proportion. Therefore, 4-MMR may be replaced with 2-MMR in dMMR screening.