Non-functional Pancreatic Neuroendocrine Tumors Surgery Strategies

Research background and purpose:Pancreatic neuroendocrine tumors(pNET)are rare tumors of the gastrointestinal tract,formerly known as islet cell tumors.Based on whether secretes hormones resulting in clinically relevant symptoms of hormone overproduction,it is divided into functional pancreatic neuroendocrine tumors(F-pNET)and non-functional pancreatic neuroendocrine tumors(NF-pNET).With the development of imaging technology,more and more small asymptomatic NF-pNET have been detected,there are different views on whether this part of tumor should be surgically removed.According to the National Comprehensive Cancer Network(NCCN)guidelines,European Neuroendocrine Tumor Society(ENETS)guidelines and Chinese guidelines for the management of pNET,the best management of tumor size<20 mm is still controversial,current studies have also reached different conclusions.Due to the difference in the anatomical location of the head and body/tail of the pancreas,their surgical approaches are different,and related studies have shown that tumors of the head have a different survival prognosis than body/tail of the pancreas.Therefore,this study investigated the following questions by retrospectively analyzing cases from the SEER database: 1.whether tumor size<20 mm NF-pNET can benefit from surgery.2.the difference in overall survival(OS)and cancer-specific survival(CSS)after surgical treatment for tumors at different locations(head and body/tail of pancreas)or not,to confirm the value of tumor location in surgical treatment strategies.This will provide some theoretical basis for the surgical treatment strategy of NF-pNET at different locations.Materials and Methods:SEER database,the full name of Surveillance Epidemiology and End Results(SEER)database,is the database of the National Cancer Institute.A unique research resource for oncology practice in the United States,the database has grown to 22 cancer registries,covering about 35% of the population of the continental United States,which covers almost all tumor categories in humans.We extracted the clinical data of NF-pNET patients from 2000 to 2018 from SEER database.By passing the inclusion and exclusion criteria,we finally obtained the basic clinical data of 6196 patients.The unbalanced baseline characteristics of patients in the pancreatic head and body/tail,we obtained clinical information of 4356 patients by 1:1 propensity score matching.The independent risk factors affecting the OS and cancer-specific survival CSS were analyzed by single multifactor COX proportional hazards model(COX).We analyzed whether there were differences in survival rates among different treatment modalities,different tumor locations and different tumor sizes,and then divided into different subgroups according to different locations and tumor sizes,and further analyzed to compare whether there were differences in survival rates among different treatment modalities.To provide some evidence-based evidence for the treatment modality of such patients,thus providing some suggestions for the treatment of <20 mm NF-pNET,and even providing clues-level help for the innovation of guidelines for NF-pNET.Result:In our cohort,6196 patients with NF-pNET were finally screened from the SEER database through inclusion and exclusion criteria.In the unmatched cohort,2316(37.4%)patients had tumor located in the pancreatic head and 3880(62.6%)in pancreatic body/tail3881(62.6%)patients underwent surgical resection,which was greater than the number of patients who did not undergo surgical resection 2315 cases(37.4%).After propensity score matching,both cohorts included 2178 cases,and the clinicopathological characteristics were well balanced.Single and multivariate analysis showed that age,anatomical location,stage,grade and surgical treatment of the primary tumor were independent risk factors for OS(P< 0.05).Single and multivariate analysis showed that age,tumor size,anatomical location,stage,grade and surgical treatment of the primary tumor were independent risk factors for CSS(P<0.05).The Kaplan-Meier survival curve analysis showed surgery significantly improved patient survival,and prognosis differed with different tumor sizes.Surgery improved the CSS(P<0.001)and OS rate(P<0.001)of patients with pancreatic head tumor size ≥10 mm,but did not improve CSS(P=0.774)and OS rate(P=0.491)of patients with tumor size <10 mm.Surgery improved the CSS(P<0.001)and OS rate(P<0.001)of patients with pancreatic body/tail tumor size ≥10 mm,as well as CSS rate(P=0.023)of patients with tumor size<10 mm.Age,anatomical location,stage,grade and surgical treatment of the primary tumor were independent risk factors for OS and CSS,and tumor size is an independent risk factor for CSS.Treatment outcomes for NF-pNETs differ depending on tumor size and location.For pancreatic head tumors,surgical resection can provide survival benefits to patients if the tumor size is ≥10 mm but cannot provide survival benefits to patients with tumor size <10 mm.Surgical resection of tumors in the body/tail of the pancreas can provide survival benefits to patients,regardless of tumor size.