Contemporary outcomes of surgical resection for chest wall chondrosarcoma.

Objective: Chondrosarcoma is the most common primary malignant chest wall tumor and is historically associated with poor prognosis. Recommendations regarding surgical excision are on the basis of small, single-institution studies. We used a large national database to assess outcomes of surgery for chest wall chondrosarcoma (CWC) hypothesizing that surgical excision remains standard of care. Methods: The National Cancer Databases for bone and soft tissue were merged to identify patients with chondrosarcoma from 2004 to 2018. Clinical and demographic characteristics of CWC were compared with chondrosarcoma from other sites. The primary outcome was overall survival described using Kaplan-Meier estimate. Univariable and multivariable Cox analysis was used to determine risk factors for poor survival among CWC patients who underwent surgery. Multivariable analysis of predictors of margin status was performed because of worse prognosis associated with positive margins. Results: Among 11,925 patients with chondrosarcoma, 1934 (16.2%) had a CWC. Relative to other sites, CWC was associated with older age, male sex, White race, surgical resection, and care at a nonacademic institution. CWC was associated with 1-, 3-, 5-, and 10-year survival of 91.5%, 82.0%, 75.5%, and 62.7%, respectively. In univariable analysis, survival was associated with surgery (hazard ratio, 0.02; P < .001) and adversely affected by positive margins (hazard ratio, 2.66; P < .001). Multivariable analysis showed larger tumor size was independently associated with increased risk for positive margins (odds ratio, 1.04; 95% CI, 1.011-1.075). Conclusions: CWC represents a different cohort of patients relative to chondrosarcoma from other sites. Surgical excision remains the optimal treatment, and positive margins are associated with poor prognosis.

Surgical subspecialization is associated with higher rate of rib fracture stabilization: a retrospective database analysis.

Background: Surgical stabilization of rib fractures (SSRF) is performed on only a small subset of patients who meet guideline-recommended indications for surgery. Although previous studies show that provider specialization was associated with SSRF procedural competency, little is known about the impact of provider specialization on SSRF performance frequency. We hypothesize that provider specialization would impact performance of SSRF. Methods: The Premier Hospital Database was used to identify adult patients with rib fractures from 2015 and 2019. The outcome of interest was performance of SSRF, defined using International Classification of Diseases-10th Revision Procedure Coding System coding. Patients were categorized as receiving their procedures from a thoracic, general surgeon, or orthopedic surgeon. Patients with missing or other provider types were excluded. Multivariate modeling was performed to evaluate the effect of surgical specialization on outcomes of SSRF. Given a priori assumptions that trauma centers may have different practice patterns, a subgroup analysis was performed excluding patients with 'trauma center' admissions. Results: Among 39 733 patients admitted with rib fractures, 2865 (7.2%) received SSRF. Trauma center admission represented a minority (1034, 36%) of SSRF procedures relative to other admission types (1831, 64%, p=0.15). In a multivariable analysis, thoracic (OR 6.94, 95% CI 5.94-8.11) and orthopedic provider (OR 2.60, 95% CI 2.16-3.14) types were significantly more likely to perform SSRF. In further analyses of trauma center admissions versus non-trauma center admissions, this pattern of SSRF performance was found at non-trauma centers. Conclusion: The majority of SSRF procedures in the USA are being performed by general surgeons and at non-trauma centers. 'Subspecialty' providers in orthopedics and thoracic surgery are performing fewer total SSRF interventions, but are more likely to perform SSRF, especially at non-trauma centers. Provider specialization as a barrier to SSRF may be related to competence in the SSRF procedures and requires further study. Type: Therapeutic/care management. Level of evidence: IV.

Robotic Lobectomy.

Robotic lobectomy volume in the United States has increased dramatically in the past 10 years. Improved perioperative outcomes and increased public demand for minimally invasive techniques continue to drive its popularity. Preoperative workup is similar to VATs lobectomy and includes appropriate tumor staging, pulmonary function tests, and imaging. Severe intraoperative complications are rare but can be catastrophic; individualized response to each is required.

Affordable Care Act Medicaid Expansion is Associated With Increased Utilization of Minimally Invasive Lung Resection for Early Stage Lung Cancer.

OBJECTIVE: Minimally invasive lung resection (MILR) is underutilized in the United States. Under the Affordable Care Act (ACA), 39 states adopted Medicaid expansion, while 12 did not. Although Medicaid expansion has been associated with improved access to cancer care, its effect on utilization of MILR is unclear. We hypothesize that MILR would increase in Medicaid expansion states. METHODS: The National Cancer Database was queried for adult patients from 2010 to 2018 with cT1/2N0M0 non-small cell lung cancer who received surgical resection by wedge, segmentectomy, or lobectomy. Patients were grouped by whether they received care in a state without Medicaid expansion vs expansion in January 2014. The outcome of interest was MILR (defined as video-assisted or robotic-assisted thoracoscopy) relative to open. Multivariable difference in differences (DID) cross-sectional analysis was used to estimate the average treatment effect (ATE) of Medicaid expansion. RESULTS: There were 41,439 patients who met inclusion criteria: 20,446 (49.3%) in expansion states and 20,993 (50.7%) in non-expansion states. Multivariable DID analysis showed that Medicaid expansion was associated with an increase in Medicaid insurance type with an ATE of 7.4% (95% CI 7.1-7.7%, P = .002). Medicaid expansion was also associated with increased MILR utilization in unadjusted analysis (10,278/20,446 (50.3%) vs 9,953/20,993 (47.4%), p < .001) and in multivariable DID analysis (ATE 0.6%, 95% CI 0.3-0.8%, P = .008). CONCLUSIONS: Although Medicaid expansion was associated with increased utilization of MILR for early stage lung cancer, the treatment effect was modest. This suggests that barriers in access to MILR are larger than simply access to care.

Statin-Induced Rhabdomyolysis Associated With Transjugular Intrahepatic Portosystemic Shunt Placement.

Rhabdomyolysis is a known rare and potentially lethal complication of statin use. This toxic effect is potentiated by alterations in hepatic physiology in patients with cirrhosis. Transjugular intrahepatic portosystemic shunt placement has the potential to further compound this effect; yet, examples of this have not previously been described in the literature. We present a case of a patient who experienced statin-induced rhabdomyolysis likely as a direct consequence of transjugular intrahepatic portosystemic shunt placement.

Implementation of Evidence-Based Presurgical Testing Guidelines in Patients Undergoing Ambulatory Surgery for Endometrial Cancer.

PURPOSE: The aim of this quality improvement intervention was to evaluate the safety and cost savings of presurgical testing (PST) guidelines for patients undergoing hysterectomy for endometrial pathology in the ambulatory setting. METHODS: Evidence-based presurgical testing (PST) guidelines were developed by a multidisciplinary team. These guidelines were implemented on the gynecologic surgery service of a comprehensive cancer center in January 2016. All patients with a diagnosis of endometrial pathology who underwent ambulatory surgery during the specified time periods were included in this analysis. A pre-post analysis was performed (preperiod, July 2014-December 2015; postperiod, July 2016-December 2017). Rates of completed presurgical tests and perioperative adverse events were compared between time periods. Cost savings related to the reduction in PST were calculated using the direct cost of testing and reported in percentage cost reduction. RESULTS: A total of 749 hysterectomies were completed in the preperiod and 775 in the postperiod. After implementation of PST guidelines, complete blood counts, coagulation testing, comprehensive metabolic panels, chest x-rays, and electrocardiograms were reduced by 13.4%, 78.1%, 36.8%, 39.0%, and 15.5%, respectively (all P < .001). Rates of perioperative cardiopulmonary adverse events (0% v 0%) and hematologic adverse events (3.3% v 2.0%; P = .10) were stable between time periods. There were no deaths within 90 days of surgery. There was a 41.4% reduction in direct costs related to PST in the postperiod. CONCLUSION: The use of evidence-based PST guidelines for patients with endometrial pathology undergoing hysterectomy in the ambulatory setting is safe and cost-effective. A multidisciplinary approach is essential for successful development and implementation.

Revisiting mouse minute virus inactivation by high temperature short time treatment.

In recent years, high temperature short time (HTST) treatment technology has been increasingly adopted for medium treatment to mitigate the potential risk of viral contamination in mammalian cell culture GMP manufacturing facilities. Mouse minute virus (MMV), also called minute virus of mice (MVM), implicated in multiple viral contamination events is commonly used as a relevant model virus to assess the effectiveness of HTST treatment of cell culture media. However, results from different studies vary broadly in inactivation kinetics as well as log reduction factors (LRFs) achieved under given treatment conditions. To determine whether the reported discrepancies stemmed from differences in MMV strains, laboratory-scale HTST devices, medium matrices, and/or experimental designs, we have taken a collaborative approach to systematically assess the effectiveness of HTST treatment for MMV inactivation. This effort was conceptualized based on a media treatment gap analysis conducted by the Consortium on Adventitious Agent Contamination in Biomanufacturing (CAACB) under the MIT Center for Biomedical Innovation (CBI). Specifically, two different MMV strains were used to evaluate the effectiveness of HTST at various treatment conditions with regard to exposure temperature and hold time duration by two independent laboratories within two different companies. To minimize experimental variations, the two sites used the same batches of MMV stocks, the same commercially purchased medium, and the same model of thermocyclers as the laboratory-scale HTST device. The two independent laboratories yielded similar MMV inactivation kinetics and comparable LRF. No significant differences were observed between the two MMV strains evaluated, suggesting that the variations from prior studies were likely due to differences in equipment, medium matrices, or other factors. The data presented here indicate that MMV inactivation by HTST treatment obeys first-order kinetics and can be mathematically modeled using an Arrhenius equation. The model-based extrapolation provides a quantitative estimate of MMV inactivation by the current industry standard HTST condition (102°C for a hold time of 10 s) used for medium treatment. Finally, based on the data from the current study and the industry experience, it is recommended that any alternative virus barrier technologies adopted for medium treatment should provide a clearance of at least 3.0 LRF based on a worst-case model virus to effectively mitigate potential risks of viral contamination.

Presence of any degree of coronary artery disease among liver transplant candidates is associated with increased rate of post-transplant major adverse cardiac events.

The impact of coronary artery disease (CAD) among liver transplant candidates (LTC) on post-LT clinical outcomes remains unclear. The aim of this study is to determine association of presence and severity of CAD on post-LT major adverse cardiac events (MACE) including cardiac-associated mortality. We conducted a retrospective cohort analysis of 231 patients who underwent diagnostic coronary angiogram (DCA) during their LT evaluation at a tertiary medical center from 2012-2017. Patients were analyzed based on degree of CAD (no CAD, non-obstructive CAD [< 50% stenosis], obstructive CAD [≥50% stenosis]) per DCA results. MACE were noted at 30 days, 1 year, 3 years, and 5 years post-LT, and Kaplan-Meier curves were used to determine post-LT MACE-free probability. LTC with any CAD, including non-obstructive CAD, had lower MACE-free probability at all post-LT time points (0.94 vs 0.65 at 30 days, P = .001; 0.87 vs 0.59 at 1 year, P = .002; 0.87 vs 0.41 at 3 years, P < .001; 0.87 vs 0.37 at 5 years, P < .001). Identification of and medical intervention for non-obstructive CAD should be considered in all LTC, though further studies are necessary to determine optimal medical interventions to mitigate MACE risk in this cohort.

Population genetics of wild Macaca fascicularis with low-coverage shotgun sequencing of museum specimens.

OBJECTIVES: Long-tailed macaques (Macaca fascicularis) are widely distributed throughout the mainland and islands of Southeast Asia, making them a useful model for understanding the complex biogeographical history resulting from drastic changes in sea levels throughout the Pleistocene. Past studies based on mitochondrial genomes (mitogenomes) of long-tailed macaque museum specimens have traced their colonization patterns throughout the archipelago, but mitogenomes trace only the maternal history. Here, our objectives were to trace phylogeographic patterns of long-tailed macaques using low-coverage nuclear DNA (nDNA) data from museum specimens. METHODS: We performed population genetic analyses and phylogenetic reconstruction on nuclear single nucleotide polymorphisms (SNPs) from shotgun sequencing of 75 long-tailed macaque museum specimens from localities throughout Southeast Asia. RESULTS: We show that shotgun sequencing of museum specimens yields sufficient genome coverage (average ~1.7%) for reconstructing population relationships using SNP data. Contrary to expectations of divergent results between nuclear and mitochondrial genomes for a female philopatric species, phylogeographical patterns based on nuclear SNPs proved to be closely similar to those found using mitogenomes. In particular, population genetic analyses and phylogenetic reconstruction from the nDNA identify two major clades within M. fascicularis: Clade A includes all individuals from the mainland along with individuals from northern Sumatra, while Clade B consists of the remaining island-living individuals, including those from southern Sumatra. CONCLUSIONS: Overall, we demonstrate that low-coverage sequencing of nDNA from museum specimens provides enough data for examining broad phylogeographic patterns, although greater genome coverage and sequencing depth would be needed to distinguish between very closely related populations, such as those throughout the Philippines.

Optimal Surgical Timing After Neoadjuvant Therapy for Stage IIIa Non-Small Cell Lung Cancer.

BACKGROUND: Patients with clinically/pathologically diagnosed stage IIIa non-small cell lung cancer (NSCLC) considered for surgery are recommended to undergo neoadjuvant chemotherapy with or without radiation. The timing of an operation after therapy is not standardized; therefore, we investigated the timing of intervention after neoadjuvant therapy and the impact on outcomes in this demographic. METHODS: The National Cancer Database was queried between 2010 and 2015 for patients with clinical/pathologic stage IIIa NSCLC. Patients were then divided into short (<77 days), mid (77-114 days), and long delay (>114 days) groups based on interquartile values. These groups were then compared for age, race, gender, insurance type, Charlson-Deyo score, length of stay, readmission rate, and overall survival based on timing of operation. RESULTS: There were 31,357 patients with clinical/pathologic stage IIIa NSCLC, and 5946 patients underwent surgical intervention. Preoperatively 3593 patients underwent chemoradiotherapy, 2185 underwent chemotherapy only, and 168 received radiation alone. The short, mid, and long delay groups were clinically and statistically similar in age, gender, insurance type, comorbidity index, treating facility type, and distance from home. Long delay groups had larger tumor size compared with other groups. Postoperative length of stay, rates of 30-day readmission, and 30- and 90-day mortality were similar across all groups. Cox modeling demonstrated a significant difference in survival when patients underwent earlier operative intervention compared with late operative intervention and when patients received chemoradiation compared with chemotherapy alone. Short, mid, and long delay group 1-year survivals were 82%, 83%, and 80% and 3-year survival 59%, 58%, and 52%, respectively (P = .0003). CONCLUSIONS: The delay in surgical resection of stage IIIa NSCLC is not associated increased early mortality; however, it is associated with worse 3-year postresection survival.

Neutrophil-to-Lymphocyte Ratio Associates Independently With Mortality in Hospitalized Patients With Cirrhosis.

BACKGROUND & AIMS: The neutrophil to lymphocyte ratio (NLR) is a biomarker of immune dysregulation in patients with cirrhosis and is inexpensive to measure. We investigated the association between NLR and mortality in hospitalized patients with cirrhosis at 4 liver transplant centers, controlling for severity of acute-on-chronic liver failure (ACLF). METHODS: We performed a retrospective study using data from the North American Consortium for the Study of End-stage Liver Disease on patients with index hospitalizations for cirrhosis from December 2011 through December 2016. We collected data on patient demographics, NLR, model for end-stage liver disease (MELD) scores, serum levels of Na, cirrhosis stages, infections, hepatocellular carcinomas, and ACLF severity (based on number of organ failures). Competing risk regression analysis evaluated mortality within 1 year after hospital discharge, accounting for competing events (liver transplant). RESULTS: At admission, the patients' mean age was 57 years, mean MELD score was 21, and mean serum level of Na was 134 mmol/L. Sixty-eight patients had no organ failure, 21 patients had 1 organ failures, 7 patients had 2 organ failures, 4 patients had 3 organ failures, and 1 patient had 4 organ failures; 36% of the patients had confirmed or suspected infections. In univariate models, risk of death associated with increasing NLR, up to a value of 8 (hazard ratio [HR]= 1.14; 95% CI, 1.07-1.20; P < .001), and NLR quartile (for NLR range of 3-5, HR = 2.17; for NLR range of >5-9, HR=2.46; for NLR quartile >9, HR=2.84 vs the lowest quartile [NLR<3]) (P ≤ .001). The NLR remained statistically significant in multivariable models, adjusting for age, MELD score, hepatocellular carcinoma, and ACLF severity. Additionally, NLR was a statistically significant independent predictor of length of index hospital stay and mortality within 90 days after discharge. CONCLUSION: In a retrospective analysis of patients with cirrhosis, we found NLR to associate with death within 1 year after non-elective hospitalization. In these patients, the risk of death associated with acute immune dysregulation persists long after their initial hospitalization.

The use of IRE in multi-modality treatment for oligometastatic pancreatic cancer.

INTRODUCTION: Pancreatic ductal adenocarcinoma (PDAC) often presents late with only 20% of patients being candidates for resection while majority already have advanced metastases with median overall survival of 3-6 months. Currently, the role of oligometastasectomy and local therapy options in PDAC is unknown in patients who have favorable response to systemic chemotherapy. The aim of this study is to analyze the survival outcome of oligometastasectomy and local IRE therapy in select patients who are treated with systemic chemotherapy for PDAC metastases. METHODS: We utilized a prospective database from 2010 to 2016 to identify patients with local surgical therapy after induction systemic chemotherapy for oligometastatic PDAC (Stage 4). The initial local therapy treatment of distant metastatic lesions was followed by adjuvant chemotherapy. Subsequently, resection of the primary PDAC in conjunction with irreversible electroporation (IRE) was performed after favorable response by RECIST criteria. RESULTS: Seven patients were identified with metastatic PDAC treated with oligometastasectomy and/or local therapy. There was single metastatic lesion in 43% (3/7) of which 57% (4/7) were localized in the liver. The treatment of the primary pancreatic cancer was performed utilizing IRE in situ in 6/7 (86%) of patients in our study with resection or radiation of oligometastasis. The median survival in our study group was 16 months with 28% (2/7) patients who remain NED (range 16-41 months). CONCLUSION: Combination of systemic chemotherapy and oligometastasectomy with adjunctive local IRE therapy is a feasible treatment strategy in highly select patients with oligometastatic PDAC that demonstrate favorable tumor biology with objective response to systemic therapy.

Development of a human cadaver model for training in laparoscopic donor nephrectomy.

BACKGROUND: The organ procurement network recommends a surgeon record 15 cases as surgeon or assistant for laparoscopic donor nephrectomies (LDN) prior to independent practice. The literature suggests that the learning curve for improved perioperative and patient outcomes is closer to 35 cases. In this article, we describe our development of a model utilizing fresh tissue and objective, quantifiable endpoints to document surgical progress, and efficiency in each of the major steps involved in LDN. MATERIALS AND METHODS: Phase I of model development focused on the modifications necessary to maintain visualization for laparoscopic surgery in a human cadaver. Phase II tested proposed learner-based metrics of procedural competency for multiport LDN by timing procedural steps of LDN in a novice learner. RESULTS: Phases I and II required 12 and nine cadavers, with a total of 35 kidneys utilized. The following metrics improved with trial number for multiport LDN: time taken for dissection of the gonadal vein, ureter, renal hilum, adrenal and lumbrical veins, simulated warm ischemic time (WIT), and operative time. CONCLUSION: Human cadavers can be used for training in LDN as evidenced by improvements in timed learner-based metrics. This simulation-based model fills a gap in available training options for surgeons.

Single Versus Double Lung Retransplantation Does Not Affect Survival Based on Previous Transplant Type.

BACKGROUND: Survival following retransplantation with a single lung is worse than after double lung transplant. We sought to characterize survival of patients who underwent lung retransplantation based on the type of their initial transplant, single or double. METHODS: The United Network for Organ Sharing database was queried for adult patients who underwent lung retransplantation from 2005 onward. Patients were excluded if they underwent more than one retransplantation. The patient population was divided into 4 groups based on first followed by second transplant type, respectively: single then single, double then single, double then double, and single then double. Descriptive analysis and Kaplan-Meier survival analysis were performed. A p value less than 0.05 was considered significant. RESULTS: A total of 410 patients underwent retransplantation in the study time period. Overall mean survival for all patients who underwent retransplantation was 1,213 days. Kaplan-Meier survival analysis demonstrated no difference in graft survival between the 4 study groups (p = 0.146). CONCLUSIONS: There was no significant difference in graft survival between recipients of retransplant with single or double lungs when stratified by previous transplant type. These results suggest that when retransplantation is performed, single lung retransplantation should be considered, regardless of previous transplant type, in an effort to maximize organ resources.

A Highly Predictive Model for Diagnosis of Colorectal Neoplasms Using Plasma MicroRNA: Improving Specificity and Sensitivity.

OBJECTIVE: To develop a plasma-based microRNA (miRNA) diagnostic assay specific for colorectal neoplasms, building upon our prior work. BACKGROUND: Colorectal neoplasms [colorectal cancer (CRC) and colorectal advanced adenoma (CAA)] frequently develop in individuals at ages when other common cancers also occur. Current screening methods lack sensitivity, specificity, and have poor patient compliance. METHODS: Plasma was screened for 380 miRNAs using microfluidic array technology from a "Training" cohort of 60 patients, (10 each) control, CRC, CAA, breast cancer, pancreatic cancer, and lung cancer. We identified uniquely dysregulated miRNAs specific for colorectal neoplasia (P < 0.05, false discovery rate: 5%, adjusted α = 0.0038). These miRNAs were evaluated using single assays in a "Test" cohort of 120 patients. A mathematical model was developed to predict blinded sample identity in a 150 patient "Validation" cohort using repeat-sub-sampling validation of the testing dataset with 1000 iterations each to assess model detection accuracy. RESULTS: Seven miRNAs (miR-21, miR-29c, miR-122, miR-192, miR-346, miR-372, and miR-374a) were selected based upon P value, area under the curve (AUC), fold change, and biological plausibility. Area under the curve (±95% confidence interval) for "Test" cohort comparisons were 0.91 (0.85-0.96) between all neoplasia and controls, 0.79 (0.70-0.88) between colorectal neoplasia and other cancers, and 0.98 (0.96-1.0) between CRC and colorectal adenomas. In our "Validation" cohort, our mathematical model predicted blinded sample identity with 69% to 77% accuracy, 67% to 76% accuracy, and 86% to 90% accuracy for each comparison, respectively. CONCLUSIONS: Our plasma miRNA assay and prediction model differentiate colorectal neoplasia from patients with other neoplasms and from controls with higher sensitivity and specificity compared with current clinical standards.

Warming to 39°C but Not to 37°C Ameliorates the Effects on the Monocyte Response by Hypothermia.

OBJECTIVE: To investigate whether warming to normal body temperature or to febrile range temperature (39°C) is able to reverse the detrimental effects of hypothermia. BACKGROUND: Unintentional intraoperative hypothermia is a well-described risk factor for surgical site infections but also sepsis. We have previously shown that hypothermia prolongs the proinflammatory response whereas normothermia and especially febrile range temperature enhance the anti-inflammatory response. METHODS: Primary human monocytes were isolated from healthy volunteers. After stimulation with LPS (Lipopolysaccharide), the monocytes were exposed to 32°C for 3  hours or 6  hours and then warmed at either 37°C or 39°C for the remaining 33  hours or 36  hours, respectively. Tumor necrosis factor α, interleukin 10, and the expression of miR-155 and miR-101 were assessed at 24  hours and 36  hours. RESULTS: Warming to 37°C does not normalize monocyte cytokine secretion within 36  hours, whereas warming to 39°C partially reverses the effects of hypothermia on monocyte function. Both miR-155 and miR-101 were suppressed after the warming episode. However, 39°C had a stronger suppressive effect than 37°C. The duration of hypothermia and the warming temperature seem to be critical for a full reversibility of the effects of hypothermia. CONCLUSION: Warming to normal body temperature (37°C) does not restore normal monocyte function in vitro. These data suggest that hypothermic patients should be warmed to febrile range temperatures. Furthermore, febrile range temperatures should be investigated as a means to modulate the inflammatory response in patients with systemic infections.

Housekeeping genes for studies of plasma microRNA: A need for more precise standardization.

INTRODUCTION: Plasma microRNAs (miRNAs) are promising biomarkers for many forms of cancer in humans; however, a fundamental concern is the lack of standardization in current data acquisition and reporting. Part of this problem lies in the use of numerous, different housekeeping genes (HKG) for the acquisition of real-time polymerase chain reaction data. This existing practice of using different HKGs generally is accepted, but reproducibility of data for comparison and validation between different laboratories calls for improvement. The need for data reproducibility standardization is crucial. An ideal plasma HKG (1) should be expressed in all samples, (2) have medium-to-high levels of expression, and (3) have consistently measurable levels of expression. METHODS: Total RNA was extracted from 200-µL plasma samples via a modified miRNeasy (QIAGEN) extraction technique with yeast carrier. Total RNA purity was assessed with a Nanodrop 2000 spectrophotometer (Thermo Scientific). The cycle threshold (Ct) was fixed at 0.03 for all samples. We investigated 10 potential HKGs based both on reports in the literature and our previous data. The potential HKGs were Let-7a, Let-7d, Let-7g, miR-16, RNU6, RNU48, miR-191, miR-223, miR-484, and miR-520d-5p. Once all samples were run for each potential HKG, the mean Ct and SD was calculated for all sample groups, allowing for comparison among HKGs. RESULTS: We screened 380 miRNAs by using microfluidic array technology (Applied Biosystems) in a discovery cohort of 20 colorectal cancer (CRC) patients, 10 patients each with breast cancer (BC), lung cancer (LC), pancreatic cancer (PC), 11 patients with colorectal adenoma, and 12 controls. The mean Ct and SD was calculated for RNU6, miR-520d-5p, miR-16, miR-191, miR-223, and miR-484, which were expressed in all samples. Let-7a, Let-7d, Let-7g, and RNU48 were only expressed in 26%, 7%, 10%, and 8% of samples, respectively, and therefore were deemed to be insufficiently reliable HKGs. Only miRNAs with >50% expression were included in this statistical analysis. U6 and miR-520d-5p had the most consistent Ct as well as the least SD. The use of both RNU6 and 520d-5p as HKGs provided reliable results. CONCLUSION: Among HKGs that were expressed in all samples, we suggest that RNU6 and miR-520d-5p were the best candidates for HKGs for studies of plasma miRNA because of the consistent and high Ct in all samples and a very narrow, reproducible SD.

Assay reproducibility in clinical studies of plasma miRNA.

There are increasing reports of plasma miRNAs as biomarkers of human disease but few standards in methodologic reporting, leading to inconsistent data. We systematically reviewed plasma miRNA studies published between July 2013-June 2014 to assess methodology. Six parameters were investigated: time to plasma extraction, methods of RNA extraction, type of miRNA, quantification, cycle threshold (Ct) setting, and methods of statistical analysis. We compared these data with a proposed standard methodologic technique. Beginning with initial screening for 380 miRNAs using microfluidic array technology and validation in an additional cohort of patients, we compared 11 miRNAs that exhibited differential expression between 16 patients with benign colorectal neoplasms (advanced adenomas) and 16 patients without any neoplasm (controls). Plasma was isolated immediately, 12, 24, 48, or 72 h following phlebotomy. miRNA was extracted using two different techniques (Trizol LS with pre-amplification or modified miRNeasy). We performed Taqman-based RT-PCR assays for the 11 miRNAs with subsequent analyses using a variable Ct setting or a fixed Ct set at 0.01, 0.03, 0.05, or 0.5. Assays were performed in duplicate by two different operators. RNU6 was the internal reference. Systematic review yielded 74 manuscripts meeting inclusion criteria. One manuscript (1.4%) documented all 6 methodological parameters, while < 5% of studies listed Ct setting. In our proposed standard technique, plasma extraction ≤12 h provided consistent ΔCt. miRNeasy extraction yielded higher miRNA concentrations and fewer non-expressed miRNAs compared to Trizol LS (1/704 miRNAs [0.14%] vs 109/704 miRNAs [15%], not expressed, respectively). A fixed Ct bar setting of 0.03 yielded the most reproducible data, provided that <10% miRNA were non-expressed. There was no significant intra-operator variability. There was significant inter-operator variation using Trizol LS extraction, while this was negligible using modified miRNeasy. For standardized reporting, we recommend plasma extraction ≤ 12 h, using modified miRNeasy extraction and utilizing a 0.03 Ct.