Faculty Bibliography

BACKGROUND:Perineural invasion (PNI) is associated with aggressive tumor behavior, increased locoregional recurrence, and decreased survival in many carcinomas. However, the significance of PNI in papillary thyroid cancer (PTC) is incompletely characterized. METHODS:Patients diagnosed with PTC and PNI from 2010-2020 at a single, academic center were identified and matched using a 1:2 scheme to patients without PNI based on gross extrathyroidal extension (ETE), nodal metastasis, positive margins, and tumor size (±4 cm). Mixed and fixed effects models were used to analyze the association of PNI with extranodal extension (ENE)-a surrogate marker of poor prognosis. RESULTS:In total, 78 patients were included (26 with PNI, 52 without PNI). Both groups had similar demographics and ultrasound characteristics preoperatively. Central compartment lymph node dissection was performed in most patients (71%, n = 55), and 31% (n = 24) underwent a lateral neck dissection. Patients with PNI had higher rates of lymphovascular invasion (50.0% vs. 25.0%, p = 0.027), microscopic ETE (80.8% vs. 44.0%, p = 0.002), and a larger burden [median 5 (interquartile range [IQR] 2-13) vs. 2 (1-5), p = 0.010] and size [median 1.2 cm (IQR 0.6-2.6) vs. 0.4 (0.2-1.4), p = 0.008] of nodal metastasis. Among patients with nodal metastasis, those with PNI had an almost fivefold increase in ENE [odds ratio [OR] 4.9 (95% confidence interval [CI] 1.5-16.5), p = 0.008] compared with those without PNI. More than a quarter (26%) of all patients had either persistent or recurrent disease over follow-up (IQR 16-54 months). CONCLUSIONS:PNI is a rare, pathologic finding that is associated with ENE in a matched cohort. Additional investigation into PNI as a prognostic feature in PTC is warranted.

UNLABELLED:A subset of thyroid cancers, recurrent differentiated thyroid cancers and anaplastic thyroid cancer (ATC), are difficult to treat by thyroidectomy and systemic therapy. A common mutation in thyroid cancer, BRAFV600E, has targetable treatment options; however, the results have been disappointing in thyroid cancers compared with BRAFV600E melanoma, as thyroid cancers quickly become resistant to BRAFV600E inhibitor (BRAFi). Here, we studied the molecular pathway that is induced in BRAFV600E thyroid cancer cells and patient-derived tumor samples in response to BRAFi, vemurafenib, using RNA-sequencing and molecular analysis. Both inducible response to BRAFi and acquired BRAFi resistance in BRAFV600E thyroid cancer cells showed significant activation of the JAK/STAT pathway. Functional analyses revealed that the combination of BRAFi and inhibitors of JAK/STAT pathway controlled BRAFV600E thyroid cancer cell growth. The Cancer Genome Atlas data analysis demonstrated that potent activation of the JAK/STAT signaling was associated with shorter recurrence rate in patients with differentiated thyroid cancer. Analysis of tumor RNA expression in patients with poorly differentiated thyroid cancer and ATC also support that enhanced activity of JAK/STAT signaling pathway is correlated with worse prognosis. Our study demonstrates that JAK/STAT pathway is activated as BRAFV600E thyroid cancer cells develop resistance to BRAFi and that this pathway is a potential target for anticancer activity and to overcome drug resistance that commonly develops to treatment with BRAFi in thyroid cancer. IMPLICATIONS:Dual inhibition of BRAF and JAK/STAT signaling pathway is a potential therapeutic treatment for anticancer activity and to overcome drug resistance to BRAFi in thyroid cancer.

Pancreatic neuroendocrine tumors (PNETs) are malignancies arising from the islets of Langerhans. Therapeutic options are limited for the over 50% of patients who present with metastatic disease. We aimed to identify mechanisms to remodel the PNET tumor microenvironment (TME) to ultimately enhance susceptibility to immunotherapy. The TMEs of localized and metastatic PNETs were investigated using an approach that combines RNA-Seq, cancer and T cell profiling, and pharmacologic perturbations. RNA-Seq analysis indicated that the primary tumors of metastatic PNETs showed significant activation of inflammatory and immune-related pathways. We determined that metastatic PNETs featured increased numbers of tumor-infiltrating T cells compared with localized tumors. T cells isolated from both localized and metastatic PNETs showed evidence of recruitment and antigen-dependent activation, suggestive of an immune-permissive microenvironment. A computational analysis suggested that vorinostat, a histone deacetylase inhibitor, may perturb the transcriptomic signature of metastatic PNETs. Treatment of PNET cell lines with vorinostat increased chemokine CCR5 expression by NF-κB activation. Vorinostat treatment of patient-derived metastatic PNET tissues augmented recruitment of autologous T cells, and this augmentation was substantiated in a mouse model of PNET. Pharmacologic induction of chemokine expression may represent a promising approach for enhancing the immunogenicity of metastatic PNET TMEs.

INTRODUCTION:Alterations in the microbiome contribute to the pathogenesis of many gastrointestinal diseases. However, the composition of the microbiome in gallbladder disease is not well described. METHODS:We aimed to characterize the biliary microbiome in cholecystectomy patients. Bile and biliary stones were collected at cholecystectomy for a variety of surgical indications between 2017 and 2019. DNA was extracted and metagenomic sequencing was performed with subsequent taxonomic classification using Kraken2. The fraction of bacterial to total DNA reads, relative abundance of bacterial species, and overall species diversity were compared between pathologies and demographics. RESULTS:A total of 74 samples were obtained from 49 patients: 46 bile and 28 stones, with matched pairs from 25 patients. The mean age was 48 years, 76% were female, 29% were Hispanic, and 29% of patients had acute cholecystitis. The most abundant species were Klebsiella pneumoniae, Staphylococcus aureus, and Streptococcus pasteurianus. The bacterial fraction in bile and stone samples was higher in acute cholecystitis compared to other non-infectious pathologies (p < 0.05). Neither the diversity nor differential prevalence of specific bacterial species varied significantly between infectious and other non-infectious gallbladder pathologies. Multivariate analysis of the non-infectious group revealed that patients over 40 years of age had increased bacterial fractions (p < 0.05). CONCLUSIONS:Metagenomic sequencing permits characterization of the gallbladder microbiome in cholecystectomy patients. Although a higher prevalence of bacteria was seen in acute cholecystitis, species and diversity were similar regardless of surgical indication. Additional study is required to determine how the microbiome can contribute to the development of symptomatic gallbladder disease.

INTRODUCTION:The incidence of papillary thyroid cancer (PTC) in the United States has tripled in the past 30 y. Polybrominated diphenyl ethers (PBDEs) are flame retardants that were ubiquitously used over that time period, and exposure to PBDEs has been associated with PTC prevalence. They are potential carcinogens via their induction of reactive oxygen species (ROS) formation and resultant deoxyribonucleic acid (DNA) damage. We sought to determine the effects of PBDE and tris(2-chloroethyl) phosphate (TCEP), another flame retardant implicated in PTC incidence, on thyrocytes in vitro and measure PBDE levels in human thyroid tissue to determine their carcinogenic potential. METHODS:Nthy-Ori, an immortalized benign human thyroid follicular cell line was used as a model of normal human thyroid. MTT assays were used to measure cell viability after exposure to PBDEs and TCEP. ROS levels and double-stranded and single-stranded DNA breaks were measured to determine genotoxicity. DNA damage response protein levels were measured with immunoblotting. RESULTS:Exposure to 20μM PBDE or TCEP for 48 h had minimal effects on thyrocyte viability. There was no significant increase in intracellular ROS up to 6 h following PBDE or TCEP exposure in thyrocytes; however, cells exposed to PBDE 47 showed evidence of DNA single-stranded and double-stranded breaks. There was a dose-dependent increase in γH2AX levels following exposure to PBDEs 47 and 209 in Nthy-Ori cells but not with TCEP treatment. CONCLUSIONS:PBDE 47 and 209 demonstrated genotoxicity but not cytotoxicity in follicular thyrocytes in vitro. Therefore, PBDE 47 and 209 may be carcinogenic in human thyroid cells.

BACKGROUND:Hiatal hernia re-approximation during index anti-reflux surgery (ARS) contributes approximately 80% of overall change in distensibility index (DI) and, potentially, compliance of the gastroesophageal (GEJ), while sphincter augmentation contributes approximately 20%. Whether this is seen in re-operative ARS is unclear. We quantify the physiologic parameters of the GEJ at each step of robotic re-operative ARS and compare these to index ARS. METHODS:Robotic ARS with hiatal hernia repair was performed on 195 consecutive patients with pathologic reflux utilizing EndoFLIP™, of which 26 previously had ARS. Intra-operative GEJ measurements, including cross-sectional area (CSA), pressure, DI, and high-pressure zone (HPZ) length were collected pre-repair, post-diaphragmatic re-approximation, post-mesh placement, and post-lower-esophageal sphincter (LES) augmentation. RESULTS:/mmHg (both p < 0.001). Pressure increased by 11.2 (IQR 4.7, 14.9) mmHg and HPZ by 1.5 (1,2) cm (both p < 0.001). These changes were similar to those seen in index ARS. Diaphragmatic re-approximation contributed to a greater percentage of overall change to the GEJ than did the augmentation procedure, with 72% of the change in DI occurring during hiatal closure, similar to that seen during index ARS. CONCLUSIONS:During re-operative ARS, dynamic intra-operative monitoring can quantify the effects of each operative step on GEJ physiologic parameters. Diaphragmatic re-approximation appears to have a greater effect on GEJ physiology than does LES-sphincter augmentation during both index and re-operative ARS.

BACKGROUND:Anti-reflux surgery (ARS) has known long-term complications, including dysphagia, bloat, and flatulence, among others. The factors affecting the development of post-operative dysphagia are poorly understood. We investigated the correlation of intra-operative esophagogastric junction (EGJ) characteristics and procedure type with post-operative dysphagia following ARS. METHODS:Robotic ARS was performed on 197 consecutive patients with pathologic reflux utilizing EndoFLIP™ technology. Intraoperative EGJ measurements including distensibility index (DI), cross-sectional area (CSA), and high-pressure zone (HPZ) length were collected. Dysphagia was assessed pre-operatively and at 3 months post-operatively. RESULTS:/mmHg (p = 0.21 and 0.16, respectively). CONCLUSIONS:Post-operative DI was similar between procedures, and there was no correlation with new or worsening post-operative dysphagia. Linx placement was associated with higher rates of new or worsening post-operative dysphagia despite a shorter post-procedure HPZ length and similar post-operative DI when compared to other methods of LES augmentation.

OBJECTIVE:We aimed to quantify the contribution of pneumoperitoneum on compliance of the esophagogastric junction (EGJ) during anti-reflux surgery. BACKGROUND:Compliance of the EGJ is reduced with anti-reflux surgery. EndoFLIP® planimetry can be used to assess dynamic changes of EGJ compliance intraoperatively. It is unclear how pneumoperitoneum impacts intraoperative measurements by EndoFLIP® and the implications thereof on validity of the results. Therefore, determining variability in EndoFLIP® measurements based on pneumoperitoneum is warranted to establish guidelines to interpret clinical outcomes. METHODS:Primary anti-reflux surgery was performed on 39 consecutive patients with pathologic reflux. Intraoperative EGJ measurements including distensibility index (DI), cross-sectional area (CSA), and intrabag pressure were collected using EndoFLIP® at 0, 10, and 15 mmHg of intraperitoneal pressure. Data were acquired pre-procedure, post-hiatal hernia repair, and post-LES augmentation with fundoplications. RESULTS:/mmHg, p = 0.002). CONCLUSION:Pneumoperitoneum affected EGJ distensibility at 15 mmHg, but not 10 mmHg, of insufflation prior to anti-reflux procedures. After anti-reflux surgery, there was a significant variance between 0 and 10 mmHg of pneumoperitoneum in pressure and distensibility. The change in pressure appears linear and needs to be considered if procedural modifications are performed based on intraoperative findings and when evaluating clinical outcomes.

BACKGROUND:Accurate self-assessment of knowledge and technical skills is key to self-directed education required in surgical training. We aimed to investigate the presence and magnitude of cognitive bias in self-assessment among a cohort of surgical interns. METHODS:First-year general surgery residents self-assessed performance on a battery of technical skill tasks (knot tying, suturing, vascular anastomosis, Fundamentals of Laparoscopic Skills peg transfer and intracorporeal suturing) at the beginning of residency. Each self-assessment was compared to actual performance. Bias and deviation were defined as arithmetic and absolute difference between actual and estimated scores. Spearman correlation assessed covariation between actual and estimated scores. Improvement in participant performance was analyzed after an end-of-year assessment. RESULTS:Participants (N = 34) completed assessments from 2017 to 2019. Actual and self-assessment scores were positively correlated (0.55, P < .001). Residents generally underestimated performance (bias -4.7 + 8.1). Participants who performed above cohort average tended to assess themselves more negatively (bias -7.3 vs -2.3) and had a larger discrepancy between self and actual scores than below average performers (deviation index 9.7 + 8.2 vs 3.8 + 3.1, P < .05). End-of-year total scores improved in 31 (91.2%) participants by an average of 11 points (90 possible). Least accurate residents in initial self-assessments (deviation indices >75th percentile) improved less than more accurate residents (median 5 vs 16 points, P < .05). All residents with a deviation index >75 percentile underestimated their performance. CONCLUSION:Cognitive bias in technical surgical skills is apparent in first-year surgical residents, particularly in those who are higher performers. Inaccuracy in self-assessment may influence improvement and should be addressed in surgical training.