Conditional Overall Survival After Diagnosis of Non-Metastatic Colon Cancer: Impact of Laterality, MSI, and KRAS Status.

BACKGROUND: The prognostic relevance of laterality, microsatellite instability (MSI), and KRAS status in colon cancer has been established. However, their effect on conditional overall survival (COS) remains unknown. METHODS: COS is the probability of surviving additional years after a time from diagnosis. The National Cancer Database (2010-2017) was queried for adults with non-metastatic colon cancer and known mutation status undergoing curative resection. COS was investigated at 2 years. RESULTS: Of 4838 patients, 3716 survived at least 2 years: 15% had stage I, 38% stage II, and 46% stage III disease. Fifty-nine percent had a right-sided tumor, 16% were MSI-high, and 37% were mutated KRAS (mKRAS). The proportion of patients alive at 2 years was higher for stage I compared with stage II and III (65 vs. 61 vs. 54%). The 5-year overall survival for stage I-III was 80, 76, and 67% for the initial cohort, and 90, 88, and 86% for those alive at 2 years. After adjustment, higher pathologic T and N stage, tumor deposits, and no chemotherapy were associated with worse COS (p < 0.01). While laterality and MSI status were not associated with COS, mKRAS was independently associated with decreased COS (HR 1.35, 95% CI 1.12-1.62). CONCLUSION: Patients with mKRAS had worse COS, suggesting that these mutations confer an aggressive biologic behavior, with patients remaining at higher risk of death 2 years after diagnosis. Routine evaluation of KRAS status should be considered in patients with non-metastatic disease for prognostication and to identify those who might benefit from modified surveillance protocols.

Performance of ChatGPT on American Board of Surgery In-Training Examination Preparation Questions.

INTRODUCTION: Chat Generative Pretrained Transformer (ChatGPT) is a large language model capable of generating human-like text. This study sought to evaluate ChatGPT's performance on Surgical Council on Resident Education (SCORE) self-assessment questions. METHODS: General surgery multiple choice questions were randomly selected from the SCORE question bank. ChatGPT (GPT-3.5, April-May 2023) evaluated questions and responses were recorded. RESULTS: ChatGPT correctly answered 123 of 200 questions (62%). ChatGPT scored lowest on biliary (2/8 questions correct, 25%), surgical critical care (3/10, 30%), general abdomen (1/3, 33%), and pancreas (1/3, 33%) topics. ChatGPT scored higher on biostatistics (4/4 correct, 100%), fluid/electrolytes/acid-base (4/4, 100%), and small intestine (8/9, 89%) questions. ChatGPT answered questions with thorough and structured support for its answers. It scored 56% on ethics questions and provided coherent explanations regarding end-of-life discussions, communication with coworkers and patients, and informed consent. For many questions answered incorrectly, ChatGPT provided cogent, yet factually incorrect descriptions, including anatomy and steps of operations. In two instances, it gave a correct explanation but chose the wrong answer. It did not answer two questions, stating it needed additional information to determine the next best step in treatment. CONCLUSIONS: ChatGPT answered 62% of SCORE questions correctly. It performed better at questions requiring standard recall but struggled with higher-level questions that required complex clinical decision making, despite providing detailed responses behind its rationale. Due to its mediocre performance on this question set and sometimes confidently-worded, yet factually inaccurate responses, caution should be used when interpreting ChatGPT's answers to general surgery questions.

ASO Author Reflections: Endoscopic Management is Reasonable for <2 cm Duodenal Neuroendocrine Tumors.

Optimal management of duodenal neuroendocrine tumors (DNETs) has not been well-defined, especially for DNETs 1-2 cm in size. Recent studies comparing endoscopic mucosal resection (EMR) and surgical resection demonstrate EMR is safe and effective for these intermediate-sized DNETs. Expert and consensus guidelines could consider updating recommendations to reflect the outcomes of EMR in DNETs and the importance of endoscopic surveillance in these patients to evaluate for local recurrence.

Is There a Role for Surgical Resection of Grade 3 Neuroendocrine Neoplasms?

BACKGROUND: Grade 3 (G3) gastroenteropancreatic (GEP) neuroendocrine neoplasms (NENs) are aggressive tumors with poor survival outcomes for which medical management is generally recommended. This study sought to evaluate outcomes of surgically treated G3 GEP-NEN patients. METHODS: A single-institutional prospective NEN database was reviewed. Patients with G3 GEP-NENs based on World Health Organization (WHO) 2019 definitions included well-differentiated neuroendocrine tumors (G3NET) and poorly differentiated neuroendocrine carcinomas (G3NEC). Clinicopathologic factors were compared between groups. Overall survival from G3 diagnosis was assessed by the Kaplan-Meier method. RESULTS: Surgical resection was performed for 463 patients (211 G1, 208 G2, 44 G3). Most had metastatic disease at presentation (54% G1, 69% G2, 91% G3; p < 0.001). The G3 cohort included 39 G3NETs and 5 G3NECs, 22 of pancreatic and 22 of midgut origin. Median overall survival (mOS; in months) was 268.1 for G1NETs, 129.9 for G2NETs, 50.5 for G3NETs, and 28.5 for G3NECs (p < 0.001). Over the same period, 31 G3 patients (12 G3NETs, 19 G3NECs) were treated non-surgically, with mOS of 19.0 for G3NETs and 12.4 for G3NECs. CONCLUSIONS: Surgical resection of G3 GEP-NENs remains controversial due to poor prognosis, and surgical series are rare. This large, single-institutional study found significantly lower mOS in patients with resected G3NENs than those with G1/G2 tumors, reflecting more aggressive tumor biology and a higher proportion with metastatic disease. The mOS for resected G3NETs and G3NECs exceeded historical non-surgical G3NEN series (mOS 11-19 months), suggesting surgery should be considered in carefully selected patients with G3NENs, especially those with well-differentiated tumors.

Management of Duodenal Neuroendocrine Tumors: Surgical versus Endoscopic Mucosal Resection.

BACKGROUND: Management of duodenal neuroendocrine tumors (DNETs) is not standardized, with smaller lesions (< 1-2 cm) generally treated by endoscopic mucosal resection (EMR) and larger DNETs by surgical resection (SR). This study reviewed how patients were selected for treatment and compared outcomes. PATIENTS AND METHODS: Patients with DNETs undergoing resection were identified through institutional databases, and clinicopathologic data recorded. χ2 and Wilcoxon tests compared variables. Survival was determined by Kaplan-Meier, and Cox regression tested association with survival. RESULTS: Among 104 patients, 64 underwent EMR and 40 had SR. Patients selected for SR had larger tumor size, younger age, and higher T, N, and M stage. There was no difference in progression-free (PFS) or overall survival (OS) between SR and EMR. In 1-2 cm DNETs, there was no difference in PFS between SR and EMR [median not reached (NR), P = 0.1]; however, longer OS was seen in SR (median NR versus 112 months, P = 0.03). In 1-2 cm DNETs, SR patients were more likely to be node-positive and younger. After adjustment for age, resection method did not correlate with survival. Comparison of surgically resected DNETs versus jejunoileal NETs revealed longer PFS (median NR versus 73 months, P < 0.001) and OS (median NR versus 119 months, P = 0.004) DISCUSSION: In 1-2 cm DNETs, there was no difference in survival between EMR and SR after adjustment for age. Recurrences could be salvaged, suggesting that EMR is a reasonable strategy. Compared with jejunoileal NETs, DNETs treated by SR had improved PFS and OS.

The Landmark Series: Management of Small Bowel Neuroendocrine Tumors.

Surgical resection is the foundation for treatment of small bowel neuroendocrine tumors (SBNETs). Guidelines for surgical management of SBNETs rely on retrospective data, which suggest that primary tumor resection and cytoreduction improve symptoms, prevent future complications, and lengthen survival. In advanced NETs, improvement in progression-free survival has been reported in large, randomized, controlled trials of various medical treatments, including somatostatin analogues, targeted therapy, and peptide receptor radionuclide therapy. This review discusses important studies influencing the management of SBNETs and the limitations of current evidence regarding surgical interventions for SBNETs.

It Is Time to Rethink Biomarkers for Surveillance of Small Bowel Neuroendocrine Tumors.

BACKGROUND: Tumor biomarkers (TBMs) reflect disease burden and correlate with survival for small bowel neuroendocrine tumors (SBNETs). This study sought to determine the performance of chromogranin A (CgA), pancreastatin (PST), neurokinin A (NKA), and serotonin (5HT) during follow-up assessment of resected SBNETs. METHODS: An institutional database identified patients undergoing surgery for SBNETs. Tumor biomarker levels were assessed as categorical (normal vs elevated) and continuous variables for association with progression-free survival (PFS) and overall survival (OS) via the Kaplan-Meier method with Cox multivariable models adjusted for confounders. Sensitivity, specificity, and predictive values of TBM levels in identifying imaging-confirmed progression were calculated. RESULTS: In 218 patients (44% female, 92% node + , 73% metastatic, 97% G1 or G2), higher levels of CgA, PST, NKA, and 5HT correlated with higher-grade and metastatic disease at presentation (p < 0.05). Elevated pre- and postoperative CgA, PST, and NKA correlated with lower PFS and OS (p < 0.05; median follow-up period, 49.6 months). Normal CgA, PST, and NKA were present in respectively 20.3%, 16.9%, and 72.6% of the patients with progression, whereas elevated levels were present in respectively 69.5%, 24.8%, and 1.3% of the patients without progression. Using TBMs to determine progression showed superiority of PST (78.9% accuracy) over CgA (63.3% accuracy) or CgA and PST together (60.3% accuracy). CONCLUSION: Although specific for progression, NKA was rarely elevated, limiting its usefulness. Pre- and postoperative PST and CgA correlated with disease burden and survival, with PST providing better discrimination of outcomes. During the follow-up period, use of PST most accurately detected progression. These results suggest that PST should replace CgA for SBNET surveillance.

NSQIP 5-factor modified frailty index and complications after ileal anal pouch anastomosis for ulcerative colitis.

Background: Frailty has been associated with worse postoperative outcomes. The 5-factor modified frailty index (mFI-5) is an objective measure although its validity in measuring frailty in patients undergoing ileal pouch-anal anastomosis (IPAA) for chronic ulcerative colitis (CUC) has not been reported. Methods: This study used the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) targeted proctectomy database. The mFI-5 was calculated by five preoperative diagnoses: insulin-dependent or noninsulin-dependent diabetes, congestive heart failure, hypertension, chronic obstructive pulmonary disease, and dependent or partially dependent functional status. The impact of mFI-5 on minor and major postoperative morbidity in CUC patients undergoing IPAA was analyzed. Results: The cohort included 1454 patients (median age 38 years, median body mass index [BMI] 26 kg/m2) of which 87 % had a mFI-5 = 0, 11 % had a mFI-5 = 1, and 2.5 % a mFI-5 ≥ 2. In multivariable logistic regression, mFI-5 ≥ 2 was significantly associated with minor complications (OR = 2.29, 95 % CI [1.00-5.22], p = 0.049), but not with major complications (p = 0.860). Conclusion: IPAA for CUC is associated with high postoperative morbidity, however, the mFI-5 alone has limited utility in determining which patients are at a higher risk of complications due to frailty. These observations suggest there is a need for more relevant instruments to measure frailty in this patient cohort.

Inhibition of serotonin biosynthesis in neuroendocrine neoplasm suppresses tumor growth in vivo.

Small bowel neuroendocrine tumors (SBNETs) originate from enterochromaffin cells in the intestine which synthesize and secrete serotonin. SBNETs express high levels of tryptophan hydroxylase 1 (Tph1), a key enzyme in serotonin biosynthesis. Patients with high serotonin level may develop carcinoid syndrome, which can be treated with somatostatin analogues and the Tph1 inhibitor telotristat ethyl in severe cases. Although the active drug telotristat can efficiently reduce serotonin levels, its effect on tumor growth is unclear. This study determined the effect of serotonin inhibition on tumor cell growth in vitro and in vivo . The levels of Tph1 in various neuroendocrine neoplasms (NENs) were determined and the biological effects of Tph1 inhibition in vitro and in vivo using genetic and pharmacologic approaches was tested. Gene and protein expression analyses were performed on patient tumors and cancer cell lines. shRNAs targeting TPH1 were used to create stable knockdown in BON cells. Control and knockdown lines were assessed for their growth rates in vitro and in vivo , angiogenesis potential, serotonin levels, endothelial cell tube formation, tumor weight, and tumor vascularity. TPH1 is highly expressed in SBNETs and many cancer types. TPH1 knockdown cells and telotristat treated cells showed similar growth rates as control cells in vitro . However, TPH1 knockdown cells formed smaller tumors in vivo and tumors were less vascularized. Although Tph1 inhibition with telotristat showed no effect on tumor cell growth in vitro , Tph1 inhibition reduced tumor formation in vivo . Serotonin inhibition in combination with other therapies is a promising new avenue for targeting metabolic vulnerabilities in NENs.

Equivalency of short-term perioperative outcomes after open, laparoscopic, and robotic ileal pouch anal anastomosis. Does procedure complexity override operative approach?

Background: Ileal pouch anal anastomosis is the treatment of choice for patients with chronic ulcerative colitis and familial adenomatous polyposis undergoing a proctocolectomy and desiring bowel continuity. It is a technically complex operation associated with significant morbidity and may be performed by an open, laparoscopic, or robotic approach. However, there is a paucity of data regarding the comparative perioperative outcomes between these 3 techniques outside of institutional studies. Methods: The NSQIP targeted proctectomy data set was used to identify patients who underwent open, laparoscopic, and robotic ileal pouch anal anastomosis between 2016 and 2019. Thirty-day outcomes between different surgical approaches were compared using univariate and multivariable analysis. Results: During the study period, 1,067 open, 971 laparoscopic, and 341 robotic ileal pouch anal anastomosis were performed. The most frequent indications were inflammatory bowel disease (64%), malignancy (18%), and familial adenomatous polyposis (7%). Mean age of the cohort was 43 ±â€¯15 years with 43% female and 76% with body mass index ≤ 30 kg/m2. Overall morbidity was 26.8% for the entire cohort with 4% anastomotic leak, 6% reoperation, 21% ileus, and 21% readmission rate. After adjusting for available confounders, operative approach was not associated with better short-term outcomes, including length of stay, overall morbidity, anastomotic leak, reoperation, incidence of ileus, and 30-day readmissions. Conclusion: Ileal pouch anal anastomosis continues to be associated with significant postoperative morbidity regardless of operative approach. Patient-related advantages in terms of perioperative outcomes for laparoscopic and robotic platforms compared to open surgery are less pronounced in complex operations such as ileal pouch anal anastomosis.

The impact of KRAS mutation, microsatellite instability, and tumor laterality on the prognosis of nonmetastatic colon cancer.

BACKGROUND: KRAS mutations, microsatellite instability, and tumor location have been found to be significant prognostic factors in colorectal cancer. The interaction between these variables and its effect on overall survival in nonmetastatic colon cancer has not been well elucidated. METHODS: The National Cancer Database (2010-2016) was queried for patients with stage I-III colon cancer and known microsatellite instability and KRAS status undergoing curative resection. RESULTS: A total of 5,292 patients were identified: 60.4% had right-sided cancers, 36.4% had KRAS mutations, and 15.6% had microsatellite instability. Right-sided tumors were more likely to have microsatellite instability and KRAS mutations compared to left-sided tumors. On univariable analysis, KRAS mutations and microsatellite instability status were not associated with differences in survival, whereas right-sided cancers had worse overall survival compared to left-sided cancers (hazard ratio 1.32, 95% confidence interval: 1.18-1.47). On multivariable analysis, right-sided location, KRAS mutations, and microsatellite instability were not independent prognostic factors. However, a significant interaction between laterality and KRAS status was observed. In patients with mutated KRAS cancers, left-sided tumors were at increased risk of death compared to right-sided tumors (hazard ratio: 1.30, 95% confidence interval: 1.03-1.63), whereas in patients with wild-type KRAS cancers, left-sided tumors were at decreased risk of death (hazard ratio: 0.81, 95% confidence interval: 0.67-0.97). CONCLUSION: In patients with stage I-III colon cancer, laterality, KRAS mutation, and microsatellite instability status were not independently prognostic after curative resection. However, the effect of laterality was opposite based on KRAS status, with left-sided (compared to right-sided) tumors associated with worse overall survival in mutated KRAS patients and better overall survival in wild-type KRAS individuals. Laterality itself may not be an independent prognostic factor but a reflection of differing genetic profiles within the colon.

Establishment of Novel Neuroendocrine Carcinoma Patient-Derived Xenograft Models for Receptor Peptide-Targeted Therapy.

Gastroenteropancreatic neuroendocrine neoplasms (GEP NENs) are rare cancers consisting of neuroendocrine carcinomas (NECs) and neuroendocrine tumors (NETs), which have been increasing in incidence in recent years. Few cell lines and pre-clinical models exist for studying GEP NECs and NETs, limiting the ability to discover novel imaging and treatment modalities. To address this gap, we isolated tumor cells from cryopreserved patient GEP NECs and NETs and injected them into the flanks of immunocompromised mice to establish patient-derived xenograft (PDX) models. Two of six mice developed tumors (NEC913 and NEC1452). Over 80% of NEC913 and NEC1452 tumor cells stained positive for Ki67. NEC913 PDX tumors expressed neuroendocrine markers such as chromogranin A (CgA), synaptophysin (SYP), and somatostatin receptor-2 (SSTR2), whereas NEC1452 PDX tumors did not express SSTR2. Exome sequencing revealed loss of TP53 and RB1 in both NEC tumors. To demonstrate an application of these novel NEC PDX models for SSTR2-targeted peptide imaging, the NEC913 and NEC1452 cells were bilaterally injected into mice. Near infrared-labelled octreotide was administered and the fluorescent signal was specifically observed for the NEC913 SSTR2 positive tumors. These 2 GEP NEC PDX models serve as a valuable resource for GEP NEN therapy testing.

Surgical Management of Neuroendocrine Tumor Liver Metastases.

Patients with neuroendocrine tumor liver metastases (NETLMs) may develop carcinoid syndrome, carcinoid heart disease, or other symptoms from overproduction of hormones. Hepatic resection and cytoreduction is the most direct treatment of NETLMs in eligible patients, and cytoreduction improves symptoms, may reduce the sequelae of carcinoid syndrome, and extends survival. Parenchymal-sparing procedures, such as ablation and enucleation, should be considered during cytoreduction to maximize treatment of multifocal tumors while preserving healthy liver tissue. For patients with large hepatic tumor burdens, high-grade disease, or comorbidities precluding surgery, liver-directed and systemic therapies can be used to palliate symptoms and improve progression-free survival.

Pancreatic Neuroendocrine Tumors: Molecular Mechanisms and Therapeutic Targets.

Pancreatic neuroendocrine tumors (pNETs) are unique, slow-growing malignancies whose molecular pathogenesis is incompletely understood. With rising incidence of pNETs over the last four decades, larger and more comprehensive 'omic' analyses of patient tumors have led to a clearer picture of the pNET genomic landscape and transcriptional profiles for both primary and metastatic lesions. In pNET patients with advanced disease, those insights have guided the use of targeted therapies that inhibit activated mTOR and receptor tyrosine kinase (RTK) pathways or stimulate somatostatin receptor signaling. Such treatments have significantly benefited patients, but intrinsic or acquired drug resistance in the tumors remains a major problem that leaves few to no effective treatment options for advanced cases. This demands a better understanding of essential molecular and biological events underlying pNET growth, metastasis, and drug resistance. This review examines the known molecular alterations associated with pNET pathogenesis, identifying which changes may be drivers of the disease and, as such, relevant therapeutic targets. We also highlight areas that warrant further investigation at the biological level and discuss available model systems for pNET research. The paucity of pNET models has hampered research efforts over the years, although recently developed cell line, animal, patient-derived xenograft, and patient-derived organoid models have significantly expanded the available platforms for pNET investigations. Advancements in pNET research and understanding are expected to guide improved patient treatments.

Metastatic pancreatic neuroendocrine tumors have decreased somatostatin expression and increased Akt signaling.

BACKGROUND: Patients with pancreatic neuroendocrine tumors often present with metastases, which reduce survival. Molecular features associated with pancreatic neuroendocrine tumor tumorigenesis have been reported, but mechanisms of metastasis remain incompletely understood. METHODS: RNA sequencing was performed on primary and metastatic pancreatic neuroendocrine tumors from 43 patients. Differentially expressed genes were identified, and quantitative polymerase chain reaction used to confirm expression differences. BON cells were transfected with short interfering RNAs and short hairpin RNAs to create knockdowns. Expression changes were confirmed by quantitative polymerase chain reaction, cell viability assessed, and protein levels evaluated by Western blot and immunofluorescence. RESULTS: Nodal and hepatic metastases had decreased expression of somatostatin compared with primary tumors (P = .003). Quantitative polymerase chain reaction in a validation cohort confirmed 5.3-fold lower somatostatin expression in hepatic metastases (P = .043) with no difference in somatostatin receptor, synaptophysin, or chromogranin A expression. Somatostatin knockdown in BON cells increased cell metabolic activity, viability, and growth. Somatostatin-knockdown cells had significantly higher levels of phosphorylated Akt protein and higher mTOR compared with controls. CONCLUSION: Pancreatic neuroendocrine tumor metastases have lower expression of somatostatin than primary tumors, and somatostatin knockdown increased growth in pancreatic neuroendocrine tumor cell lines. This was associated with increased activation of Akt, identifying this pathway as a potential mechanism by which loss of somatostatin expression promotes the metastatic phenotype.