Objective To investigate the efficacy of adjuvant chemotherapy for patients with duodenal adenocarcinoma (DAC) at different stages. Methods A retrospective analysis was performed on patients diagnosed with DAC between January 2000 and December 2021 using data from the SEER database. Kaplan-Meier curves were utilized to evaluate the impact of adjuvant chemotherapy on survival outcomes in DAC patients with different stages. Univariate and multivariate COX regression analyses were performed to determine whether adjuvant chemotherapy served as an independent prognostic factor for cancer-specific survival (CSS) and overall survival (OS). Results A total of 1 195 patients meeting the inclusion criteria were included in the study. Of these, 620 patients (51.9%) received adjuvant chemotherapy after surgery were defined as the adjuvant chemotherapy group, whereas 575 patients (48.1%) underwent surgery alone were defined as the other group. After propensity score matching, 634 patients were retained for subsequent analysis. Subgroup analysis demonstrated that there were statistically significant differences in CSS and OS between the adjuvant chemotherapy group and other group for stage ⅢA and ⅢB patients (P < 0.05), while no statistically significant differences in CSS and OS between the adjuvant chemotherapy group and other group for stageⅠ, stageⅡA, stage ⅡB patients (P > 0.05). Multivariate analysis identified adjuvant chemotherapy as an independent protective factor for both CSS and OS in DAC patients. Additionally, age, year of diagnosis, tumor grade, number of regional lymph nodes examined (RNE), and TNM stage were identified as independent protective or risk factors for CSS and OS (all P < 0.05). Conclusions Based on substage stratification, the survival benefits of adjuvant chemotherapy for DAC patients are as follows: patients with stage ⅢA and ⅢB benefit in both CSS and OS, while patients with stage Ⅰ, Ⅱ A, and ⅡB do not benefit in either CSS or OS.

Objective To study the component ratios of pancreatic carcinoma,and prognosis of patients with the different pathological types.Methods The data of 92 011 pancreatic carcinoma patients who were diagnosed by the definite pathological method from 2004 to 2014 were extracted from the US SEER database.The life table was used to calculate the 1-,3-and 5-year survival rates.The Kaplan-Meier was used to construct the survival curves of the patients.The Cox univariate analysis was applied to evaluate the HR of the different pathological types,and the x2 test and independent sample t-test were used to evaluate the base line data.Results The overall 5-year survival of 92 011 pancreatic carcinoma patients was 7.6％.The median survival time was 8.8 months and the component ratios of the pancreatic ductal adenocarcinoma (PDAC),pancreatic epithelium cancer bedside the PDAC,neuroendocrine tumors,undifferentiated carcinoma,mesenchymal carcinoma and rare cancer unclassified were 85.78％,6.40％,6.67％,0.97％,0.10％ and 0.08％,respectively.The differences were statistically significant between the baseline data such as age,gender,race and position (P ＜ 0.05).The overall 5-year survivals of the PDAC,pancreaticepithelium cancer beside the PDAC,neuroendocrine tumors,undifferentiated carcinoma,mesenchymal carcinoma and rare cancer unclassified were 4.2％,13.4％,49.2％,5.0％,29.2％ and 24.5％,respectively,and the median survival times were 5 months,7 months,58 months,2 months,26 months and 7 months respectively.The distant metastasis rate of neuroendocrine carcinoma was the lowest (35.0％).The undifferentiated carcinoma was the most prone to distant metastases (65.2％).Basically,half of the other types of pancreatic cancer had metastasis at the time of diagnosis.In pancreatic epithelium cancer beside the PDAC,the high to low 5-year survival rates were solid pseudopapillary carcinoma (87.3％),cystadenocarcinoma (36.8％),intraductal papillary mucinous neoplasm (36.5％),acinar cell carcinoma (20.0％),and pancreatic adenocarcinoma mixed with other subtypes (19.7％).The incidence of the other types of pancreatic carcinoma was less than 8％,such as mucinous carcinoma,squamous cell carcinoma,adenosquamous carcinoma and signet ring cell carcinoma.In neuroendocrine tumor,the 5-year survival rate of insulinoma (77.1％) was higher than those of neuroendocrine tumor (malignant) (NET,62.0％) and neuroendocrine carcinoma (NEC,46.5％).Conclusion The prognosis of pancreatic carcinoma was poor,and the pathological types had a significant impact on the prognosis of the patients.