Classification performance bias between training and test sets in a limited mammography dataset.

OBJECTIVES: To assess the performance bias caused by sampling data into training and test sets in a mammography radiomics study. METHODS: Mammograms from 700 women were used to study upstaging of ductal carcinoma in situ. The dataset was repeatedly shuffled and split into training (n = 400) and test cases (n = 300) forty times. For each split, cross-validation was used for training, followed by an assessment of the test set. Logistic regression with regularization and support vector machine were used as the machine learning classifiers. For each split and classifier type, multiple models were created based on radiomics and/or clinical features. RESULTS: Area under the curve (AUC) performances varied considerably across the different data splits (e.g., radiomics regression model: train 0.58-0.70, test 0.59-0.73). Performances for regression models showed a tradeoff where better training led to worse testing and vice versa. Cross-validation over all cases reduced this variability, but required samples of 500+ cases to yield representative estimates of performance. CONCLUSIONS: In medical imaging, clinical datasets are often limited to relatively small size. Models built from different training sets may not be representative of the whole dataset. Depending on the selected data split and model, performance bias could lead to inappropriate conclusions that might influence the clinical significance of the findings. ADVANCES IN KNOWLEDGE: Performance bias can result from model testing when using limited datasets. Optimal strategies for test set selection should be developed to ensure study conclusions are appropriate.

Development of a Competency Framework Defining Effective Surgical Educators.

OBJECTIVE: The objective of this study is to develop a practical framework of competencies and behaviors which define an effective surgical educator. DESIGN: A modified Delphi approach was used. A literature review and series of discussions with surgical education experts led to creation of a survey instrument which was sent to surgical faculty and trainees from a single academic institution. The results from this initial survey informed the creation of the subsequent survey instrument which was also sent to surgical faculty and trainees. Focus groups with surgical faculty and residents were conducted separately, transcribed, deidentified, and then evaluated for recurring themes. A competency framework was developed. SETTING: The surveys were administered and focus groups were conducted at the University Hospitals Cleveland Medical Center, a tertiary care academic institution. PARTICIPANTS: Residents, fellows, and faculty surgeons from the fields of general surgery, plastic surgery, vascular surgery, orthopedic surgery, otolaryngology, neurosurgery, and urology. RESULTS: There were 115 responses (31.3%) from 367 faculty surgeons, residents, and fellows invited to complete the initial survey examining 50 competencies. Eighteen competencies received a mean Likert score of at least 4 by both faculty and residents and were included in the subsequent survey instrument which was completed by 72 participants (19.6%). Focus groups were held separately with 6 faculty surgeons and 6 residents. Analysis of the survey results and focus group discussions identified several themes which informed the development of a competency framework consisting of 5 overarching competencies as well as 16 specific behaviors. CONCLUSIONS: A practical framework was developed consisting of 5 competencies and 16 behaviors which define an effective surgical educator. The 5 competencies are: 1) fosters psychological safety, 2) displays exemplary medical knowledge and patient care, 3) diagnoses the learner and adjusts teaching, 4) communicates thought process to trainee, and 5) displays learner-centeredness. Based on the competency framework, residency leadership may specifically tailor faculty development initiatives to improve surgical education programming.

Molecular subtypes of high-grade serous ovarian cancer across racial groups and gene expression platforms.

Introduction: High-grade serous carcinoma (HGSC) gene expression subtypes are associated with differential survival. We characterized HGSC gene expression in Black individuals and considered whether gene expression differences by race may contribute to poorer HGSC survival among Black versus non-Hispanic White individuals. Methods: We included newly generated RNA-Seq data from Black and White individuals, and array-based genotyping data from four existing studies of White and Japanese individuals. We assigned subtypes using K-means clustering. Cluster- and dataset-specific gene expression patterns were summarized by moderated t-scores. We compared cluster-specific gene expression patterns across datasets by calculating the correlation between the summarized vectors of moderated t-scores. Following mapping to The Cancer Genome Atlas (TCGA)-derived HGSC subtypes, we used Cox proportional hazards models to estimate subtype-specific survival by dataset. Results: Cluster-specific gene expression was similar across gene expression platforms. Comparing the Black study population to the White and Japanese study populations, the immunoreactive subtype was more common (39% versus 23%-28%) and the differentiated subtype less common (7% versus 22%-31%). Patterns of subtype-specific survival were similar between the Black and White populations with RNA-Seq data; compared to mesenchymal cases, the risk of death was similar for proliferative and differentiated cases and suggestively lower for immunoreactive cases (Black population HR=0.79 [0.55, 1.13], White population HR=0.86 [0.62, 1.19]). Conclusions: A single, platform-agnostic pipeline can be used to assign HGSC gene expression subtypes. While the observed prevalence of HGSC subtypes varied by race, subtype-specific survival was similar.

The Association between Mediated Deprivation and Ovarian Cancer Survival among African American Women.

BACKGROUND: Deprivation indices are often used to adjust for socio-economic disparities in health studies. Their role has been partially evaluated for certain population-level cancer outcomes, but examination of their role in ovarian cancer is limited. In this study, we evaluated a range of well-recognized deprivation indices in relation to cancer survival in a cohort of self-identified Black women diagnosed with ovarian cancer. This study aimed to determine if clinical or diagnostic characteristics lie on a mediating pathway between socioeconomic status (SES) and deprivation and ovarian cancer survival in a minority population that experiences worse survival from ovarian cancer. METHODS: We used mediation analysis to look at the direct and indirect causal effects of deprivation indices with main mediators of the SEER stage at diagnosis and residual disease. The analysis employed Bayesian structural equation models with variable selection. We applied a joint Bayesian structural model for the mediator, including a Weibull mixed model for the vital outcome with deprivation as exposure. We selected modifiers via a Monte Carlo model selection procedure. RESULTS: The results suggest that high SES-related indices, such as Yost, Kolak urbanicity (URB), mobility (MOB) and SES dimensions, and concentrated disadvantage index (CDI), all have a significant impact on improved survival. In contrast, area deprivation index (ADI)/Singh, and area level poverty (POV) did not have a major impact. In some cases, the indirect effects have very wide credible intervals, so the total effect is not well estimated despite the estimation of the direct effect. CONCLUSIONS: First, it is clear that commonly used indices such as Yost, or CDI both significantly impact the survival experience of Black women diagnosed with epithelial ovarian cancer. In addition, the Kolak dimension indices (URB, MOB, mixed immigrant: MICA and SES) also demonstrate a significant association, depending on the mediator. Mediation effects differ according to the mediator chosen.

Growth Dynamics of Ductal Carcinoma in Situ Recapitulate Normal Breast Development.

Ductal carcinoma in situ (DCIS) and invasive breast cancer share many morphologic, proteomic, and genomic alterations. Yet in contrast to invasive cancer, many DCIS tumors do not progress and may remain indolent over decades. To better understand the heterogenous nature of this disease, we reconstructed the growth dynamics of 18 DCIS tumors based on the geo-spatial distribution of their somatic mutations. The somatic mutation topographies revealed that DCIS is multiclonal and consists of spatially discontinuous subclonal lesions. Here we show that this pattern of spread is consistent with a new 'Comet' model of DCIS tumorigenesis, whereby multiple subclones arise early and nucleate the buds of the growing tumor. The discontinuous, multiclonal growth of the Comet model is analogous to the branching morphogenesis of normal breast development that governs the rapid expansion of the mammary epithelium during puberty. The branching morphogenesis-like dynamics of the proposed Comet model diverges from the canonical model of clonal evolution, and better explains observed genomic spatial data. Importantly, the Comet model allows for the clinically relevant scenario of extensive DCIS spread, without being subjected to the selective pressures of subclone competition that promote the emergence of increasingly invasive phenotypes. As such, the normal cell movement inferred during DCIS growth provides a new explanation for the limited risk of progression in DCIS and adds biologic rationale for ongoing clinical efforts to reduce DCIS overtreatment.

Accuracy in Polyp Size Measurement Among Surgeons, Gastroenterologists, Trainees, and Experts: A Prospective Video-Based Study.

INTRODUCTION: Polyp size determination plays an important role in endoscopic decision making and follow-up determination. However, there is a lack of knowledge of endoscopist accuracy for polyp sizing and efficacy of available tools for size measurement. Our aim was to compare the accuracy of visual assessment, snare, forceps, and virtual scale endoscope (VSE) in estimating polyp size among a diverse group of endoscopists. METHODS: We conducted a prospective video-based study. One hundred twenty polyps measured and recorded along with all available measurement tools were randomized to visual assessment, snare, forceps, or VSE group. Eleven endoscopists conducted video-based measurement using the randomized measurement tool. Primary outcome was relative accuracy in polyp size measurement compared with caliper measurement immediately postresection. RESULTS: One thousand three hundred twenty measurements were performed. VSE had statistically significantly higher relative accuracy when compared to forceps (79.3 vs 71.3%; P < 0.0001). Forceps had statistically significantly higher relative accuracy when compared to visual assessment (71.3 vs 63.6%; P = 0.0036). There was no statistically significant difference when comparing visual assessment and snare-based measurements (63.6 vs 62.8%; P = 0.797). Overall, 21.5% of polyps >5 mm were misclassified as ≤5 mm and 17.3% of polyps ≥10 mm were misclassified as <10 mm. VSE had the lowest percentage of polyps >5 mm misclassified as ≤5 mm (2.6%), polyps ≤5 mm misclassified as >5 mm (5.1%), and polyps <10 mm misclassified as ≥10 mm (1.7%). DISCUSSION: Visual size estimation of polyps is inaccurate independently of training level, sex, and specialty. Size measurement accuracy can be improved using forceps and yields the highest relative accuracy when an adaptive scale technology is used.

Association of inflammation-related exposures and ovarian cancer survival in a multi-site cohort study of Black women.

BACKGROUND: An association was observed between an inflammation-related risk score (IRRS) and worse overall survival (OS) among a cohort of mostly White women with invasive epithelial ovarian cancer (EOC). Herein, we evaluated the association between the IRRS and OS among Black women with EOC, a population with higher frequencies of pro-inflammatory exposures and worse survival. METHODS: The analysis included 592 Black women diagnosed with EOC from the African American Cancer Epidemiology Study (AACES). Cox proportional hazards models were used to compute hazard ratios (HRs) and 95% confidence intervals (CIs) for the association of the IRRS and OS, adjusting for relevant covariates. Additional inflammation-related exposures, including the energy-adjusted Dietary Inflammatory Index (E-DIITM), were evaluated. RESULTS: A dose-response trend was observed showing higher IRRS was associated with worse OS (per quartile HR: 1.11, 95% CI: 1.01-1.22). Adding the E-DII to the model attenuated the association of IRRS with OS, and increasing E-DII, indicating a more pro-inflammatory diet, was associated with shorter OS (per quartile HR: 1.12, 95% CI: 1.02-1.24). Scoring high on both indices was associated with shorter OS (HR: 1.54, 95% CI: 1.16-2.06). CONCLUSION: Higher levels of inflammation-related exposures were associated with decreased EOC OS among Black women.

Archival single-cell genomics reveals persistent subclones during DCIS progression.

Ductal carcinoma in situ (DCIS) is a common precursor of invasive breast cancer. Our understanding of its genomic progression to recurrent disease remains poor, partly due to challenges associated with the genomic profiling of formalin-fixed paraffin-embedded (FFPE) materials. Here, we developed Arc-well, a high-throughput single-cell DNA-sequencing method that is compatible with FFPE materials. We validated our method by profiling 40,330 single cells from cell lines, a frozen tissue, and 27 FFPE samples from breast, lung, and prostate tumors stored for 3-31 years. Analysis of 10 patients with matched DCIS and cancers that recurred 2-16 years later show that many primary DCIS had already undergone whole-genome doubling and clonal diversification and that they shared genomic lineages with persistent subclones in the recurrences. Evolutionary analysis suggests that most DCIS cases in our cohort underwent an evolutionary bottleneck, and further identified chromosome aberrations in the persistent subclones that were associated with recurrence.

Deprivation and segregation in ovarian cancer survival among African American women: a mediation analysis.

PURPOSE: Deprivation and segregation indices are often examined as possible explanations for observed health disparities in population-based studies. In this study, we assessed the role of recognized deprivation and segregation indices specifically as they affect survival in a cohort of self-identified Black women diagnosed with ovarian cancer who enrolled in the African American Cancer Epidemiology Study. METHODS: Mediation analysis was used to examine the direct and indirect effects between deprivation or segregation and overall survival via a Bayesian structural equation model with Gibbs variable selection. RESULTS: The results suggest that high socioeconomic status-related indices have an association with increased survival, ranging from 25% to 56%. In contrast, index of concentration at the extremes-race does not have a significant impact on overall survival. In many cases, the indirect effects have very wide credible intervals; consequently, the total effect is not well estimated despite the estimation of the direct effect. CONCLUSIONS: Our results show that Black women living in higher socioeconomic status neighborhoods are associated with increased survival with ovarian cancer using area-level economic indices such as Yost or index of concentration at the extremes-income. In addition, the Kolak urbanization index has a similar impact and highlights the importance of area-level deprivation and segregation as potentially modifiable social factors in ovarian cancer survival.

Symptom duration is not associated with per oral endoscopic myotomy (POEM) failure.

INTRODUCTION: Per oral endoscopic myotomy (POEM) is a relatively novel technique to address achalasia; however, little is known about the efficacy of POEM for patients with long-standing achalasia. We hypothesize that patients with long-standing achalasia prior to intervention will be more recalcitrant to POEM than patients with symptoms for a short duration. METHODS: We performed a retrospective analysis of patients with achalasia who received a POEM at a single institution from 2012 to 2022. Patients were grouped into cohorts based on the time of symptom duration: < 1 year, 1-3 years, 4-10 years, > 10 years. POEM failure was defined as need for repeat intervention, symptom recurrence, and a high postoperative Eckart score. Demographic and clinical data were compared between cohorts. Measures of failure multivariable logistic regression analyzed the association between symptom duration and response to POEM. RESULTS: During the study period, 132 patients met inclusion criteria. Patient age at surgery, sex, BMI, Charleston-Deyo Comorbidity Index, and patients with diabetes with and without end organ complications, connective tissue diseases, and patients with ulcer diseases did not differ among cohorts. Patients who have had symptoms for greater than 10 years had significantly more endoscopic interventions prior to their POEM (30% vs, 60% p = 0.002). Patients in all cohorts experienced the same number of symptoms post-POEM. Manometric measurements did not vary across cohorts after POEM. Symptom recurrence, need for repeat endoscopic intervention, repeat surgical intervention, or repeat POEM also did not vary across cohorts. Having symptoms of achalasia > 10 years did not increase the odds POEM failure on multivariable logistical regression. CONCLUSIONS: These data suggest that longer symptom duration is not associated with increased rates of POEM failure. This is promising as clinicians should not exclude patients for POEM eligibility based on duration of symptoms alone.

Microcalcification crystallography as a potential marker of DCIS recurrence.

Ductal carcinoma in-situ (DCIS) accounts for 20-25% of all new breast cancer diagnoses. DCIS has an uncertain risk of progression to invasive breast cancer and a lack of predictive biomarkers may result in relatively high levels (~ 75%) of overtreatment. To identify unique prognostic biomarkers of invasive progression, crystallographic and chemical features of DCIS microcalcifications have been explored. Samples from patients with at least 5-years of follow up and no known recurrence (174 calcifications in 67 patients) or ipsilateral invasive breast cancer recurrence (179 microcalcifications in 57 patients) were studied. Significant differences were noted between the two groups including whitlockite relative mass, hydroxyapatite and whitlockite crystal maturity and, elementally, sodium to calcium ion ratio. A preliminary predictive model for DCIS to invasive cancer progression was developed from these parameters with an AUC of 0.797. These results provide insights into the differing DCIS tissue microenvironments, and how these impact microcalcification formation.

Do preoperative endoscopic interventions predict symptom recurrence or reintervention after peroral endoscopic myotomy?

BACKGROUND: Studies assessing outcomes of patients undergoing peroral endoscopic myotomy (POEM) after botulinum injection or dilation have had various results with respect to failure, although this has not been differentiated between lack of clinical response and recurrence. We hypothesize that patients with previous endoscopic intervention(s) are more likely to recur than treatment-naïve patients. METHODS: This is a retrospective cohort study of patients that underwent POEM for achalasia at a single tertiary care center between 2011 and 2022. Patients were excluded if they had previous myotomy (POEM or Heller). The remaining patients were stratified into treatment-naïve patients (TN), those with previous botulinum injection (BTX), those with previous dilatation (BD), and those with both previous endoscopic interventions (BOTH). Primary outcome was recurrence indicated by clinical symptoms or need for repeat endoscopic intervention or surgery after originally having clinical resolution (Eckardt ≤ 3). Multivariate logistic regression using preoperative and intraoperative factors was completed to assess odds of recurrence. RESULTS: A total of 164 patients were included in the analysis, 90 TN, 34 BD, 28 BTX, and 12 BOTH. There were no other significant differences in demographics or in preoperative Eckardt score (p = 0.53). There was no difference in the proportion of patients that had postoperative manometry (p = 0.74), symptom recurrence (p = 0.59), surgical intervention (p = 0.16). BTX (14.3%) and BOTH (16.7%) patients had a higher rate of repeat endoscopic intervention than BD and TN patients (5.9% and 1.1%). In the logistic regression analysis, there was no association among the BTX, BD, or BOTH groups compared to the TN group. No odds ratios achieved statistical significance. CONCLUSIONS: There were no increased likelihood of recurrence with botulinum injection or dilatation prior to POEM, implying that they are similarly good candidates compared to treatment-naïve patients.

Preoperative manometric data can predict symptom improvement after per oral endoscopic myotomy for treatment of achalasia.

BACKGROUND: While per oral endoscopic myotomy (POEM) has been shown to be efficacious in the treatment of achalasia, it can be difficult to predict who will have a robust and durable response. Historically, high lower esophageal sphincter pressures have been shown to predict a worse response to endoscopic therapies such as botox therapy. This study was designed to evaluate if modern preoperative manometric data could predict a response to therapy after POEM. METHODS: This was a retrospective study of 144 patients who underwent a POEM at a single institution by a single surgeon over an 8-year period (2014-2022) who had high-resolution manometry performed preoperatively and had an Eckardt symptom score performed both preoperatively and postoperatively. The achalasia type and integrated relaxation pressures (IRP) were then tested for potential correlation with need for any further achalasia interventions postoperatively as well as the degree of Eckardt score reduction using univariate analysis. RESULTS: The achalasia type on preoperatively manometry was not predictive of need for further interventions or degree of Eckardt score reduction (p = 0.74 and 0.44, respectively). A higher IRP was not predictive of need for further interventions however it was predictive of a greater reduction in postoperative Eckardt scores (p = 0.03) as shown by a nonzero regression slope. CONCLUSION: In this study, achalasia type was not a predictive factor in need for further interventions or degree of symptom relief. While IRP was not predictive of need for further interventions, a higher IRP did predict better symptomatic relief postoperatively. This result is opposite that of other endoscopic treatment modalities. Therefore, patients with higher IRP on high-resolution manometry would likely benefit from myotomy which provides significant symptomatic relief postoperatively.

Preoperative patient factors and anatomy do not predict who will develop reflux after per oral endoscopic myotomy.

BACKGROUND: Per oral endoscopic myotomy (POEM) has been shown to be an efficacious and safe therapy for the treatment of achalasia. Compared to laparoscopic Heller myotomy however, no antireflux procedure is routinely combined with POEM and therefore the development of symptomatic or silent reflux is of concern. This study was designed to determine if various patient factors and anatomy would predict the development of gastroesophageal reflux disease post-operatively. METHODS: This was a retrospective cohort study of all patients who underwent a POEM at a single institution by a single surgeon over an eight-year period (2014-2022). It has been our practice to obtain a postoperative ambulatory pH test on all patients 6 months after POEM off all acid reducing medications. Patients without a postoperative ambulatory esophageal pH monitoring test were excluded. Age, sex, obesity (BMI > 30), achalasia type, presence of a hiatal hernia, history of prior endoscopic achalasia treatments or myotomy were analyzed using univariate analysis as predictive factors for the development of postoperative GERD (DeMeester score > 14.7 on ambulatory pH monitoring). RESULTS: There were 179 total patients included in the study with 42 patients (23.5%) having undergone postoperative ambulatory pH testing. The majority of patients (137 or 76.5%) were lost to follow up and did not undergo ambulatory pH testing. Twenty-three out of those 42 patients (55%) had evidence of GERD on ambulatory pH testing. Multiple preoperative patient characteristics including demographics, manometric results, EGD findings, and history of prior achalasia interventions did not correlate with the development of post-operative GERD. CONCLUSIONS: Despite the high rate of reflux after POEM, there does not appear to be any reliable preoperative indicators of which patients have a higher risk of developing post-operative GERD after POEM.

Risk factors for adverse outcomes following paraesophageal hernia repair among obese patients.

BACKGROUND: Although obesity is an established risk factor for adverse outcomes after paraesophageal hernia repair (PEHR), many obese patients nonetheless receive PEHR. The purpose of this study was to explore risk factors for adverse outcomes of PEHR among this high-risk cohort. We hypothesized that obese patients may have other risk factors for adverse outcomes following PEHR. METHODS: A retrospective study of adult obese patients who underwent minimally invasive PEHR from 2017 to 2019 was performed. Patients were excluded for BMI < 30 or if they had concomitant bariatric surgery at time of PEHR. The primary outcome of interest was a composite adverse outcome (CAO) defined as having any of the four following outcomes after PEHR: persistent GERD > 30 d, persistent dysphagia > 30 d, recurrence, or reoperation. Chi-square and t-test analysis was used to compare demographic and clinical characteristics. Multivariable logistic regression analysis was used to evaluate independent predictors of CAO. RESULTS: In total, 139 patients met inclusion criteria with a median follow-up of 19.7 months (IQR 8.8-81). Among them, 51/139 (36.7%) patients had a CAO: 31/139 (22.4%) had persistent GERD, 20/139 (14.4%) had persistent dysphagia, 24/139 (17.3%) had recurrence, and 6/139 (4.3%) required reoperation. On unadjusted analysis, patients with a CAO were more likely to have a history of prior abdominal surgery (86.3% vs 70.5%, p = 0.04) and were less likely to have undergone a preoperative CT scan (27.5% vs 45.5%, p = 0.04). On multivariable analysis, previous abdominal surgery was independently associated with an increased likelihood of CAO whereas age and preoperative CT scan had a decreased likelihood of CAO. CONCLUSIONS: Although there were adverse outcomes among obese patients, minimally invasive PEHR may be feasible in a subset of patients at specialized centers. These findings may help guide the appropriate selection of obese patients for PEHR.

Ipsilateral Lesion Detection Refinement for Tomosynthesis.

Computer-aided detection (CAD) frameworks for breast cancer screening have been researched for several decades. Early adoption of deep-learning models in CAD frameworks has shown greatly improved detection performance compared to traditional CAD on single-view images. Recently, studies have improved performance by merging information from multiple views within each screening exam. Clinically, the integration of lesion correspondence during screening is a complicated decision process that depends on the correct execution of several referencing steps. However, most multi-view CAD frameworks are deep-learning-based black-box techniques. Fully end-to-end designs make it very difficult to analyze model behaviors and fine-tune performance. More importantly, the black-box nature of the techniques discourages clinical adoption due to the lack of explicit reasoning for each multi-view referencing step. Therefore, there is a need for a multi-view detection framework that can not only detect cancers accurately but also provide step-by-step, multi-view reasoning. In this work, we present Ipsilateral-Matching-Refinement Networks (IMR-Net) for digital breast tomosynthesis (DBT) lesion detection across multiple views. Our proposed framework adaptively refines the single-view detection scores based on explicit ipsilateral lesion matching. IMR-Net is built on a robust, single-view detection CAD pipeline with a commercial development DBT dataset of 24675 DBT volumetric views from 8034 exams. Performance is measured using location-based, case-level receiver operating characteristic (ROC) and case-level free-response ROC (FROC) analysis.

An analysis of publications originating from abstracts presented at the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) Meeting.

BACKGROUND: Research presentation has benefits, including CV building, networking, and collaboration. A measurable standard for achievement is publication in a peer-reviewed journal. Expectations regarding the likelihood of publication are unknown for studies presented at a national surgical scientific meeting. This study aims to evaluate predictors of manuscript publication arising from abstracts presented at a national surgical scientific meeting. METHODS: Abstracts presented at the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) Meeting 2019 were reviewed. Identification of published manuscripts was completed using MedLine, Embase, and Google Scholar 28 months after the presentation to allow for time for publication. Factors evaluated for association with publication included author and abstract measures. Descriptive analyses and multivariable statistics were performed. RESULTS: 724 abstracts (160 podiums, 564 posters) were included. Of the podium presentations, 128 (80%) were published in a median of 4 months after the presentation. On univariable and multivariable analyses, there was no association between publication and abstract topic, gender, degree, number of publications, or H-indices of first and senior authors. 154 (27.3%) poster presentations were published with a median of 13 months. On univariable analysis, there was a statistically significant difference regarding the abstract topic (p = 0.015) and senior author degree (p = 0.01) between published and unpublished posters. Multivariable analysis demonstrated that colorectal surgery (OR 2.52; CI 1.02-6.23) and metabolic/obesity (OR 2.53; CI 1.09-5.84) are associated with an increased odd of publication. There was an inverse association with female senior authors (OR 0.53; CI 0.29-0.98), while additional degrees (e.g., doctorate and/or master's degree) of the senior authors were associated with an increased publication rate (OR 1.80; CI 1.00-3.22). CONCLUSION: 80% of podiums but only 27% of posters were ultimately published. While some predictors of poster publication were noted, it is unclear if these are why these projects fail to publish. Future research is warranted to determine if there are effective strategies to increase poster publication rates.

Classification performance bias between training and test sets in a limited mammography dataset.

Objectives: To assess the performance bias caused by sampling data into training and test sets in a mammography radiomics study. Methods: Mammograms from 700 women were used to study upstaging of ductal carcinoma in situ. The dataset was repeatedly shuffled and split into training (n=400) and test cases (n=300) forty times. For each split, cross-validation was used for training, followed by an assessment of the test set. Logistic regression with regularization and support vector machine were used as the machine learning classifiers. For each split and classifier type, multiple models were created based on radiomics and/or clinical features. Results: Area under the curve (AUC) performances varied considerably across the different data splits (e.g., radiomics regression model: train 0.58-0.70, test 0.59-0.73). Performances for regression models showed a tradeoff where better training led to worse testing and vice versa. Cross-validation over all cases reduced this variability, but required samples of 500+ cases to yield representative estimates of performance. Conclusions: In medical imaging, clinical datasets are often limited to relatively small size. Models built from different training sets may not be representative of the whole dataset. Depending on the selected data split and model, performance bias could lead to inappropriate conclusions that might influence the clinical significance of the findings. Optimal strategies for test set selection should be developed to ensure study conclusions are appropriate.