ObjectiveTo define hyaluronidase treatment parameters that efficiently remove the extracellular matrix from zygotes without impairing embryo development， thereby providing a basis for standardized assisted reproductive procedures. MethodsMouse zygotes were treated with hyaluronidase at 40， 80， or 120 IU/mL for 60， 90， or 120 s. Following treatment， embryos were cultured in Krebs-ringer bicarbonate-based solution for organismal media （KSOM） medium， and blastocyst formation was monitored using a Time-lapse imaging system. ResultsA concentration of 40 IU/mL was insufficient for effective matrix removal， whereas 120 IU/mL markedly reduced blastocyst formation. In contrast， 80 IU/mL achieved efficient matrix clearance with minimal impact on development. Blastocyst rates were comparable between the 60 s and 90 s groups， with a slight advantage for the 60 s under the experimental conditions. ConclusionHyaluronidase treatment at 80 IU/mL for 60 s represents optimal processing conditions for mouse zygotes. These findings provide experimental basis and standardized reference for embryo handling in assisted reproductive technologies.

BACKGROUND:One of the advantages of clear aligner treatment is molar distalization.However,tooth tilting movement and loss of anterior anchorage may occur during treatment.There are few studies on whether these problems can be improved by selecting clear aligners with different thicknesses and edges to improve the clinical treatment effect.OBJECTIVE:To analyze the control ability of clear aligners with different thickness and edges on the central incisor,lateral incisor,and second molar when pushing the maxillary second molar distally by three-dimensional finite element analysis.METHODS:Three-dimensional finite element analysis models of bilateral maxillary second molar distalization with clear aligner,maxillary dentition,periodontal ligament,and alveolar bone with different thicknesses and margins were established by Mimics,Geomagic Wrap,3-matic and SolidWorks software,respectively.There were 16 combinations of four thicknesses(0.4,0.5,0.625,and 0.75 mm)and four margins(scallop,straight,straight extension 2 mm and straight extension 4 mm).The data were imported into Ansys Workbench software for design and solution.The mean value,peak value and distribution of the periodontal ligament equivalent stress of the second molar,the equivalent stress and the maximum initial displacement of the second molar,and the control ability of each appliance on the second molar,central incisor,and lateral incisor were analyzed.RESULTS AND CONCLUSION:(1)The mean equivalent stress of periodontal ligament of the second molar,the equivalent stress of the second molar and the maximum initial displacement of the second molar increased with the extension of the appliance edge and the increase of the thickness of the appliance in the 16 groups of models.(2)When the thickness of appliances was the same,the maximum equivalent stress of the second molar in the linear appliance group was the highest,and the maximum equivalent stress of the second molar in the linear extended appliance group was greater than that in the scallop appliance group.When the edge of the appliance was the same,the periodontal ligament equivalent stress peak of the second molar increased with the increase of the thickness of the appliance.The equivalent stress distribution in the periodontal ligament of the second molar in the linear extendable appliance group was more uniform than that in the scallop appliance group and the linear appliance group.(3)When the thickness of the appliance was the same,the scallop-shaped appliance had the worst control on the second molar.When the edge of the appliance was the same,with the increase of the thickness of the appliance,the control of the second molar by the linear extender appliance was gradually stronger than that by the linear appliance.The control of the central incisor was stronger and more stable with the linear extended 2 mm appliance,while the control of the lateral incisor was stronger and more stable with the linear appliance.(4)The results showed that when using clear aligners to push molars distally,extending the edge of the appliance could improve the control of the molars and reduce the tilting movement of the teeth.The design of a straight extension margin of 2 mm for the central incisor and a straight edge for the lateral incisor can enhance the control of the anchorage incisor and reduce the labial inclination of the anterior teeth.

BACKGROUND:The quadriceps strength of patients with osteoporosis and sarcopenia is significantly reduced,which can further reduce the function of the knee joint,affect the function of the lower limbs and even lead to a decrease in whole-body coordination.It is speculated that a reasonable quadriceps training program and personalized guidance are beneficial to the recovery of knee joint function in patients with osteoporosis and sarcopenia.OBJECTIVE:To observe the effect of short-term moderate-intensity resistance rehabilitation training on the mass and function of the quadriceps and knee joint function in patients with osteoporosis and sarcopenia.METHODS:Using the integrated physical examination and rehabilitation model,375 patients with osteoporosis and sarcopenia were screened at the Health Management Center of Shanghai Public Health Clinical Center.They underwent 12 weeks of combined/comprehensive exercise rehabilitation based on resistance exercise,including quadriceps resistance isotonic and isometric contraction training twice a week(3-5 sets each time,10-15 minutes per set)and aerobic exercise/balance exercise two or three times a week(30 minutes each time).Assessments and data collection were performed before rehabilitation training,12 weeks after rehabilitation training,and at follow-up 12 weeks after stopping rehabilitation training,mainly including knee joint range of motion and proprioception,quadriceps muscle strength,and cross-sectional area(magnetic resonance imaging results),pain,knee joint function(Hospital for Special Surgery score)and walking function("up-and-go"time and 6 m pace test results)as well as the patient's psychological status assessment.RESULTS AND CONCLUSION:All 375 patients completed 12 weeks of rehabilitation training and 12 weeks of follow-up without any adverse events.(1)Compared with before training,the patients' gait speed and knee range of motion increased significantly after 12 weeks of rehabilitation training(P＜0.01),the time of"stand-to-walk"decreased(P＜0.01),and the proprioception of the knee joint and the strength of the quadriceps femoris were significantly improved(P＜0.01);and at the follow-up visit 12 weeks after stopping training,the above indicators and functions of the patients were well maintained(P＞0.05).(2)Magnetic resonance imaging results showed that the effective cross-sectional area of the quadriceps femoris did not improve significantly after 12 weeks of rehabilitation training(P＞0.05);but the Hospital for Special Surgery score of knee joint function increased significantly(P＜0.01),and the visual analog pain scale score decreased significantly(P＜0.01),suggesting that this may be related to the improvement of quadriceps femoris quality by resistance rehabilitation training.(3)The results of the Hospital Anxiety and Depression Scale score showed that the anxiety and depression scores of the patients continued to decrease,both at 12 weeks of rehabilitation training and at 12 weeks after stopping training(P＜0.01).It is suggested that resistance rehabilitation training of the quadriceps can help patients with osteoporosis and sarcopenia to restore quadriceps muscle strength,increase range of motion,improve proprioception and joint stability,thereby enhancing knee joint function,reducing pain,improving depression and anxiety,and to a certain extent promoting the coordinated recovery of the musculoskeletal system.

AIM: To investigate the influence of pterygium thickness and area on corneal refractive status.METHODS: Prospective longitudinal study. A total of 60 cases(60 eyes)of pterygium patients admitted to our hospital from January 2024 to September 2024 were randomly selected. All patients underwent pterygium excision combined with pedicle conjunctival flap transplantation for treatment. Optical coherence tomography(OCT)was used to measure the preoperative thickness of patient's pterygium, and a digital slit lamp microscope was used to measure the area of pterygium. The corneal refractive status(degree of corneal astigmatism and average curvature)and changes in uncorrected visual acuity of patients before surgery, 1 d, 1, and 3 mo after surgery were compared. The relationship between preoperative thickness and area of pterygium in patients and corneal refractive status indicators at different postoperative time points were analyzed, and Logistic regression was used to analyze the impact of pterygium thickness and area on postoperative visual improvement in patients.RESULTS: All patients completed follow-up after surgery for 3 mo. At 3 mo after surgery, visual acuity improved in 21 eyes(35%). The results of bivariate Pearson correlation analysis showed that the thickness and area of pterygium positively correlated with the degree of corneal astigmatism and uncorrected visual acuity before surgery and 1 d, 1, and 3 mo after surgery(all P<0.05), and negatively correlated with the average corneal curvature before surgery and 1 d, 1, and 3 mo after surgery(all P<0.05). Logistic regression analysis showed that the thickness and area of pterygium before surgery, high degree of corneal astigmatism, and low uncorrected visual acuity(large LogMAR value)were all risk factors for poor postoperative visual improvement in patients(OR>1, P<0.05). The large average corneal curvature before surgery was a protective factor for poor postoperative visual improvement in patients(OR<1, P<0.05).CONCLUSION: The increase in thickness and area of pterygium can, to some extent, improve corneal astigmatism, reduce the average curvature of the cornea, and affect postoperative visual recovery.

BACKGROUND:One of the advantages of clear aligner treatment is molar distalization.However,tooth tilting movement and loss of anterior anchorage may occur during treatment.There are few studies on whether these problems can be improved by selecting clear aligners with different thicknesses and edges to improve the clinical treatment effect.OBJECTIVE:To analyze the control ability of clear aligners with different thickness and edges on the central incisor,lateral incisor,and second molar when pushing the maxillary second molar distally by three-dimensional finite element analysis.METHODS:Three-dimensional finite element analysis models of bilateral maxillary second molar distalization with clear aligner,maxillary dentition,periodontal ligament,and alveolar bone with different thicknesses and margins were established by Mimics,Geomagic Wrap,3-matic and SolidWorks software,respectively.There were 16 combinations of four thicknesses(0.4,0.5,0.625,and 0.75 mm)and four margins(scallop,straight,straight extension 2 mm and straight extension 4 mm).The data were imported into Ansys Workbench software for design and solution.The mean value,peak value and distribution of the periodontal ligament equivalent stress of the second molar,the equivalent stress and the maximum initial displacement of the second molar,and the control ability of each appliance on the second molar,central incisor,and lateral incisor were analyzed.RESULTS AND CONCLUSION:(1)The mean equivalent stress of periodontal ligament of the second molar,the equivalent stress of the second molar and the maximum initial displacement of the second molar increased with the extension of the appliance edge and the increase of the thickness of the appliance in the 16 groups of models.(2)When the thickness of appliances was the same,the maximum equivalent stress of the second molar in the linear appliance group was the highest,and the maximum equivalent stress of the second molar in the linear extended appliance group was greater than that in the scallop appliance group.When the edge of the appliance was the same,the periodontal ligament equivalent stress peak of the second molar increased with the increase of the thickness of the appliance.The equivalent stress distribution in the periodontal ligament of the second molar in the linear extendable appliance group was more uniform than that in the scallop appliance group and the linear appliance group.(3)When the thickness of the appliance was the same,the scallop-shaped appliance had the worst control on the second molar.When the edge of the appliance was the same,with the increase of the thickness of the appliance,the control of the second molar by the linear extender appliance was gradually stronger than that by the linear appliance.The control of the central incisor was stronger and more stable with the linear extended 2 mm appliance,while the control of the lateral incisor was stronger and more stable with the linear appliance.(4)The results showed that when using clear aligners to push molars distally,extending the edge of the appliance could improve the control of the molars and reduce the tilting movement of the teeth.The design of a straight extension margin of 2 mm for the central incisor and a straight edge for the lateral incisor can enhance the control of the anchorage incisor and reduce the labial inclination of the anterior teeth.

BACKGROUND:The quadriceps strength of patients with osteoporosis and sarcopenia is significantly reduced,which can further reduce the function of the knee joint,affect the function of the lower limbs and even lead to a decrease in whole-body coordination.It is speculated that a reasonable quadriceps training program and personalized guidance are beneficial to the recovery of knee joint function in patients with osteoporosis and sarcopenia.OBJECTIVE:To observe the effect of short-term moderate-intensity resistance rehabilitation training on the mass and function of the quadriceps and knee joint function in patients with osteoporosis and sarcopenia.METHODS:Using the integrated physical examination and rehabilitation model,375 patients with osteoporosis and sarcopenia were screened at the Health Management Center of Shanghai Public Health Clinical Center.They underwent 12 weeks of combined/comprehensive exercise rehabilitation based on resistance exercise,including quadriceps resistance isotonic and isometric contraction training twice a week(3-5 sets each time,10-15 minutes per set)and aerobic exercise/balance exercise two or three times a week(30 minutes each time).Assessments and data collection were performed before rehabilitation training,12 weeks after rehabilitation training,and at follow-up 12 weeks after stopping rehabilitation training,mainly including knee joint range of motion and proprioception,quadriceps muscle strength,and cross-sectional area(magnetic resonance imaging results),pain,knee joint function(Hospital for Special Surgery score)and walking function("up-and-go"time and 6 m pace test results)as well as the patient's psychological status assessment.RESULTS AND CONCLUSION:All 375 patients completed 12 weeks of rehabilitation training and 12 weeks of follow-up without any adverse events.(1)Compared with before training,the patients' gait speed and knee range of motion increased significantly after 12 weeks of rehabilitation training(P＜0.01),the time of"stand-to-walk"decreased(P＜0.01),and the proprioception of the knee joint and the strength of the quadriceps femoris were significantly improved(P＜0.01);and at the follow-up visit 12 weeks after stopping training,the above indicators and functions of the patients were well maintained(P＞0.05).(2)Magnetic resonance imaging results showed that the effective cross-sectional area of the quadriceps femoris did not improve significantly after 12 weeks of rehabilitation training(P＞0.05);but the Hospital for Special Surgery score of knee joint function increased significantly(P＜0.01),and the visual analog pain scale score decreased significantly(P＜0.01),suggesting that this may be related to the improvement of quadriceps femoris quality by resistance rehabilitation training.(3)The results of the Hospital Anxiety and Depression Scale score showed that the anxiety and depression scores of the patients continued to decrease,both at 12 weeks of rehabilitation training and at 12 weeks after stopping training(P＜0.01).It is suggested that resistance rehabilitation training of the quadriceps can help patients with osteoporosis and sarcopenia to restore quadriceps muscle strength,increase range of motion,improve proprioception and joint stability,thereby enhancing knee joint function,reducing pain,improving depression and anxiety,and to a certain extent promoting the coordinated recovery of the musculoskeletal system.

Objective:To investigate the survival outcomes and prognostic factors in patients undergoing radical resection for pancreatic body and tail cancer.Methods:A retrospective case series study was conducted on 992 patients who underwent radical resection for pancreatic body and tail cancer at the Pancreatic Center of the First Affiliated Hospital of Nanjing Medical University from January 2016 to June 2024. In this study, 577 (58.2%) were male and 415 (41.8%) were female,with an age of (65±9) years (range: 26 to 86 years). Follow-up continued until June 2024. Survival rates were estimated using the Kaplan-Meier method,and prognostic factors were identified using univariate and multivariate Cox proportional hazards models.Results:Among 992 patients,open surgery was the predominant approach (89.1%, 884/992), and radical antegrade modular pancreatosplenectomy (RAMPS) was performed in 317 patients (32.0%). Combined organ resection,venous resection,and arterial resection were performed in 23.5%, 9.3%,and 11.2% of patients,respectively. The rates of R0, R1-1 mm, and R1-direct resections were 49.8% (494/992),41.5% (412/992), and 8.7% (86/992),respectively. Stage ⅡB was the most common TNM stage (32.2%,319/992). A total of 801 patients (80.8%) received adjuvant chemotherapy. The median follow-up period was 32.0(8.8) months(range:3.2 to 105.3 months),during which 508 patients (51.2%) died. The overall median survival (OS) was 26.4 months,with 1-,3-, and 5-year survival rates of 79.0%,40.0%, and 29.0%, respectively. In the recent five years (from 2020 to 2024), the median OS improved significantly to 34.1 months compared to 20.0 months from 2016 to 2019 ( P<0.01). Histological subtype analysis showed that the median OS time was 26.7 months for pancreatic ductal adenocarcinoma (PDAC, n=855),58.9 months for invasive intraductal papillary mucinous carcinoma (IPMC, n=32),and 15.7 months for adenosquamous carcinoma of pancreas (ASCP, n=73) ( P=0.001). Among PDAC patients, adjuvant chemotherapy significantly improved survival (29.1 months vs. 14.4 months, P<0.01);in IPMC patients, adjuvant chemotherapy also extended survival (65.7 months vs. 58.9 months, P=0.047). Although ASCP patients receiving chemotherapy had a longer median OS time than those without (18.8 months vs. 8.9 months),the difference was not statistically significant ( P=0.151). Multivariate Cox regression analysis in PDAC patients indicated that adjuvant chemotherapy, R0 resection, T stage,N stage,and tumor differentiation were independent prognostic factors ( P<0.01). The median OS time by TNM stage was:not reached for stage ⅠA, 51.6 months for ⅠB, 25.5 months for ⅡA, 23.7 months for ⅡB, 23.0 months for Ⅲ, and 14.4 months for Ⅳ. The median OS time for R0,R1-1 mm,and R1-direct resections was 34.1,24.7,and 15.7 months,respectively ( P<0.01). Conclusion:Adjuvant chemotherapy,R0 resection,tumor stage,and differentiation are independent prognostic factors for pancreatic body and tail cancer.

Objective:To investigate the survival outcomes and prognostic factors in patients undergoing radical resection for pancreatic body and tail cancer.Methods:A retrospective case series study was conducted on 992 patients who underwent radical resection for pancreatic body and tail cancer at the Pancreatic Center of the First Affiliated Hospital of Nanjing Medical University from January 2016 to June 2024. In this study, 577 (58.2%) were male and 415 (41.8%) were female,with an age of (65±9) years (range: 26 to 86 years). Follow-up continued until June 2024. Survival rates were estimated using the Kaplan-Meier method,and prognostic factors were identified using univariate and multivariate Cox proportional hazards models.Results:Among 992 patients,open surgery was the predominant approach (89.1%, 884/992), and radical antegrade modular pancreatosplenectomy (RAMPS) was performed in 317 patients (32.0%). Combined organ resection,venous resection,and arterial resection were performed in 23.5%, 9.3%,and 11.2% of patients,respectively. The rates of R0, R1-1 mm, and R1-direct resections were 49.8% (494/992),41.5% (412/992), and 8.7% (86/992),respectively. Stage ⅡB was the most common TNM stage (32.2%,319/992). A total of 801 patients (80.8%) received adjuvant chemotherapy. The median follow-up period was 32.0(8.8) months(range:3.2 to 105.3 months),during which 508 patients (51.2%) died. The overall median survival (OS) was 26.4 months,with 1-,3-, and 5-year survival rates of 79.0%,40.0%, and 29.0%, respectively. In the recent five years (from 2020 to 2024), the median OS improved significantly to 34.1 months compared to 20.0 months from 2016 to 2019 ( P<0.01). Histological subtype analysis showed that the median OS time was 26.7 months for pancreatic ductal adenocarcinoma (PDAC, n=855),58.9 months for invasive intraductal papillary mucinous carcinoma (IPMC, n=32),and 15.7 months for adenosquamous carcinoma of pancreas (ASCP, n=73) ( P=0.001). Among PDAC patients, adjuvant chemotherapy significantly improved survival (29.1 months vs. 14.4 months, P<0.01);in IPMC patients, adjuvant chemotherapy also extended survival (65.7 months vs. 58.9 months, P=0.047). Although ASCP patients receiving chemotherapy had a longer median OS time than those without (18.8 months vs. 8.9 months),the difference was not statistically significant ( P=0.151). Multivariate Cox regression analysis in PDAC patients indicated that adjuvant chemotherapy, R0 resection, T stage,N stage,and tumor differentiation were independent prognostic factors ( P<0.01). The median OS time by TNM stage was:not reached for stage ⅠA, 51.6 months for ⅠB, 25.5 months for ⅡA, 23.7 months for ⅡB, 23.0 months for Ⅲ, and 14.4 months for Ⅳ. The median OS time for R0,R1-1 mm,and R1-direct resections was 34.1,24.7,and 15.7 months,respectively ( P<0.01). Conclusion:Adjuvant chemotherapy,R0 resection,tumor stage,and differentiation are independent prognostic factors for pancreatic body and tail cancer.

Objective:To investigate the influencing factors and prognosis of early recurrence after gastrectomy for gastric cancer.Methods:The retrospective cohort study was conducted. The clinicopathological data of 2 078 patients who underwent gastrectomy for gastric cancer at six medical centers across China, including Fudan University Shanghai Cancer Center et al, between January 2012 and June 2023 were collected. There were 1 449 males and 629 females, aged (59±11) years. Patients were classified as early recurrence and late recurrence based on the time of post-operative recurrence. Observation indicators: (1) comparison of clinicopathological characteristics between gastric cancer patients with different recurrence types; (2) recurrence and metastasis of tumor; (3) survival of patients after postoperative recurrence of gastric cancer; (4) analysis of influencing factors for early recurrence after gastrectomy for gastric cancer. Comparison of measurement data with normal distribution between groups was conducted using the independent sample t test. Comparison of measurement data with skewed distribution between groups was conducted using the Mann-Whitney U test. Comparison of count data between groups was conducted using the chi-square test. Comparison of ordinal data between groups was conducted using the rank sum test. Multivariate analysis was conducted using the Logistic regression model. Kaplan-Meier method was used to calculate survival rate and plot survival curve, and Log-rank test was used for survival analysis. Results:(1) Comparison of clinicopathological characteristics between gastric cancer patients with different recurrence types. Among the 2 078 patients, 1 452 cases had early recurrence and 626 cases had late recurrence. There were significant differences in preoperative carcinoembryonic antigen, preoperative CA19-9, preoperative CA72-4, preoperative albumin, tumor diameter, neoadjuvant therapy, R 0 resection, combined organ resection, scope of gastric resection, nerve and vessel infiltration, degree of tumor differentiation, pathological N staging, pathological TNM staging between early and late recurrence patients ( P<0.05). (2) Recurrence and metastasis of tumor. Among the 2 078 patients, 200 cases had local recurrence, 1 213 cases had hematogenous metastases, 392 cases had distant lymph node metastases, and 731 cases had peritoneal metastases. Among the 1 452 early recurrence patients, 142 cases had local recurrence, 834 cases had hematogenous metastases, 289 cases had distant lymph node metastases, and 507 cases had peritoneal metastases. Among the 626 late recurrence patients, 58 cases had local recurrence, 379 cases had hematogenous metastases, 103 cases had distant lymph node metastases, and 224 cases had peritoneal metastases. One patient may have multiple forms of recurrence and metastasis. There was no significant difference in the above indica-tors between early and late recurrence patients ( χ2=0.13, 1.74, 3.40, 0.14, P>0.05). (3) Survival of patients after postoperative recurrence of gastric cancer. All 2 078 patients were followed up until death after recurrence, with a follow-up time of 31(range, 9?147)months. The 1-, 2-, 3-, and 5-year overall survival rates after recurrence were 33.5%, 17.2%, 10.1%, and 3.3% in early recurrence patients, versus 44.2%, 21.6%, 12.8%, and 5.8% in late recurrence patients, respectively, showing a significant difference in overall survival after recurrence between the two groups ( hazard ratio=0.84, 95% confidence interval as 0.76?0.92, P<0.05). (4) Analysis of influencing factors for early recurrence after gastrectomy for gastric cancer. Results of multivariate analysis showed that combined organ resection, total gastrectomy, pathological TNM staging as stage Ⅲ were independent risk factors for early recurrence after gastrectomy for gastric cancer ( odds ratio=1.31, 1.32, 1.34, 95% confidence interval as 1.01?1.70, 1.06?1.65, 1.05?1.71, P<0.05) and normal preoperative tumor markers, neoadjuvant therapy, R 0 resection were independent protective factors for early recurrence ( odds ratio=0.61, 0.50, 0.38, 95% confidence interval as 0.49?0.76, 0.35?0.72, 0.25?0.58, P<0.05). Conclusions:Compared with patients with late recurrence after gastric cancer surgery, patients with early recurrence have a poor prognosis, in which liver metastases is more common. Combine organ resection, total gastrectomy, pathological TNM staging as stage Ⅲ are independent risk factors for early recurrence, and normal preoperative tumor markers, neoadjuvant therapy, R 0 resection are independent protective factors for early recurrence after gastrectomy for gastric cancer.

Objective:To explore the prognosis after radical resection for stage Ⅰ gastric cancer and the application value of adjuvant chemotherapy.Methods:The retrospective cohort study was conducted. The clinicopathological data of 3 353 patients with stage Ⅰ gastric cancer who were admitted to Fudan University Shanghai Cancer Center from January 2000 to December 2022 were collected. There were 2 369 males and 984 females, aged 60(range, 21-91) years. All patients underwent radical R 0 resection. Observation indicators: (1) clinicopathological characteristics of patients; (2) influencing factors for postoperative prognosis of patients; (3) prognostic analysis of patients; (4) construction and validation of a predictive model for the efficacy of postoperative adjuvant chemotherapy. Comparison of count data between groups was conducted using the chi-square test. Univariate and multivariate analyses were performed using the Cox proportional hazards regression model. The Kaplan-Meier method was used to calculate survival rates and draw survival curves, and the Log-rank test was used for survival analysis. Based on the multivariate analysis result, a nomogram prediction model was constructed to predict survival benefit. Results:(1) Clinicopatho-logical characteristics of patients. The highly, moderately, and poorly differentiated tumors were observed in 16, 234, 396 cases of 646 patients aged <50 years and 279, 1 617, 811 cases of 2 707 pati-ents aged ≥50 years, respectively, showing a significant difference in degree of tumor differentiation between them ( P<0.05). For 297 patients in stage T1N1M0, cases aged <50 years and ≥50 years were 71 and 226, cases of males and females were 184 and 113, cases with negative and positive vascular invasion were 37 and 260, cases with negative and positive nerve invasion were 275 and 22, cases without and with postoperative adjuvant chemotherapy were 222 and 75, respectively. The above indicators for 678 patients in stage T2N0M0 105, 573, 533, 145, 517, 161, 526, 152, 563, 115, respectively. There were significant differences in the above indicators between the two groups ( P<0.05). (2) Influencing factors for postoperative prognosis of patients. Results of multivariate analysis showed that age ≥50 years, stage T2, moderately differentiated tumor, the number of lymph nodes dissected <16, positive vascular invasion, carcinoembryonic antigen (CEA) ≥5 μg/L, and CA19-9 ≥37 U/mL were independent risk factors for disease-free survival (DFS) after surgery for stage Ⅰ gastric cancer ( hazard ratio=4.600, 1.555, 1.835, 1.362, 1.451, 1.571, 2.134, 95% confidence interval as 2.806-7.541, 1.205-2.006, 1.016-3.314, 1.059-1.753, 1.057-1.993, 1.100-2.243, 1.257-3.625, P<0.05). Age ≥50 years, stage T2, the number of lymph nodes dissected <16, positive vascular invasion, CEA ≥5 μg/L, and CA19-9 ≥37 U/mL were independent risk factors for overall survival (OS) after surgery for stage Ⅰ gastric cancer ( hazard ratio=5.208, 1.597, 1.373, 1.520, 1.464, 2.356, 95% confidence interval as 3.028-8.955, 1.231-2.072, 1.060-1.777, 1.099-2.104, 1.004-2.134, 1.385-4.009, P<0.05). Postoperative adjuvant chemotherapy was an independent protective factor for both DFS and OS after surgery for stage I gastric cancer ( hazard ratio=0.361 0.297, 95% confidence interval as 0.177-0.736, 0.131-0.674, P<0.05). (3) Prognostic analysis of patients. According to the results of multi-variate analysis, among 3 353 patients, there were significant differences in 5-year DFS rate and 10-year OS rate between patients aged <50 years and ≥50 years ( P<0.05). There were significant differences in 5-year DFS rate and 10-year OS rate among patients in TNM stage ⅠA and ⅠB ( P<0.05). There were significant differences in 5-year DFS rate and 10-year OS rate among patients in stage T1N0M0, T1N1M0, T2N0M0 ( P<0.05). There were significant differences in 5-year DFS rate and 10-year OS rate among patients with the highly, moderately, and poorly differentiated tumors ( P<0.05). There were significant differences in 5-year DFS rate and 10-year OS rate among patients with the number of lymph lodes dissected <16 and ≥16 ( P<0.05). There were significant differences in 5-year DFS rate and 10-year OS rate between patients with negative and positive vascular invasion ( P<0.05). There were significant differences in 5-year DFS rate and 10-year OS rate between patients with and without postoperative adjuvant chemotherapy ( P<0.05), among patients in stage T1N0M0, T1N1M0, T2N0M0 who received no postoperative adjuvant chemotherapy ( P<0.05). For patients in stage T1N1M0, there was no significant difference in 5-year DFS rate and 10-year OS rate between patients with and without postoperative adjuvant chemotherapy ( P>0.05).Results of stratified analysis showed that for patients aged ≥ 50 years, there were significant differences in 5-year DFS rate and 10-year OS rate between patients with and without postoperative adjuvant chemotherapy ( P<0.05). For patients in stage T2N0M0, there were significant differences in 5-year DFS rate and 10-year OS rate between patients with and without postoperative adjuvant chemotherapy ( P<0.05). For patients with positive vascular invasion, there were significant differences in 5-year DFS rate and 10-year OS rate between patients with and without postoperative adjuvant chemotherapy ( P<0.05). (4) Construction and validation of a predictive model for the efficacy of adjuvant chemotherapy. A nomogram predictive model was constructed based on the multivariate analysis results of OS and used for calculating net benefits and distribution. Among the 3 096 patients without postoperative adjuvant chemotherapy, 1 009 cases had a predicted net benefit of >5%-10%, and 250 patients had a predicted net benefit >10%. The predicted survival analysis further verified that the predicted benefit of adjuvant chemotherapy was consistent with the prognosis of patients. Conclusions:Patients with age ≥50 years, stage T2 tumors, moderately differentiated tumor, the number of lymph nodes dissected <16, positive vascular invasion have worse survival prognosis postoperative. Postoperative adjuvant chemotherapy provides better prognosis in high-risk patients. Patients in stage T1N1M0 have lower recurrence and survival risks, of whom with 1 metastatic lymph node is more suitable for follow-up rather than postoperative adjuvant chemotherapy.