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    guanl@stanford.edu
    University - Student Department: School of Medicine Position: Graduate, Medicine

All Publications

  • Brain metastases from esophageal cancer: A retrospective review from a single institution. World neurosurgery Touponse, G. C., Li, G., Tai, J. W., Rodrigues, A. J., Granucci, M., Burnside, G., Bhambhvani, H. P., Han, S. S., Ji, H. P., Gephart, M. H. 2024

    Abstract

    Patients with brain metastases (BrM) from esophageal cancer have poor prognosis, the incidence of which is expected to rise due to improved survival from the primary tumor and increased neuroimaging. We aimed to identify patient and esophageal cancer characteristics associated with shorter survival in patients with BrM and, secondly, to compare the prognosis of patients with HER2 overexpression.We retrospectively reviewed patients with BrM from esophageal cancer at a single institution from 2008-2021. We collected patient demographics, primary tumor and BrM characteristics, and treatment. Our primary outcome was median survival from the time of BrM.The median age at primary diagnosis was 66.5 years and 86% were male. Of the 49 patients, 71% had adenocarcinoma, 20% squamous cell carcinoma and 8% other. 71% of patients presented with stage III or IV disease, including 16% with synchronous primary and BrM. The median time to BrM was 10.1 months (IQR 1.7-22.8) and the median survival from BrM was 8.4 months (95%CI 4.8-16.8). On multivariable analysis, treatment with stereotactic radiosurgery (HR=0.19;p=0.04), surgical resection (HR 0.24;p=0.03) and immunotherapy (HR 0.19;p=0.04) were associated with increased survival while KPS ≤70 (HR=13.2;p<0.001) was associated with decreased survival. HER2 overexpression was found in 22% of patients, but we noted no survival difference (5.2 months HER2+ versus 9.8 months HER2neg;p=0.95).The median survival from esophageal-to-brain metastasis was 8.4 months. Patients with a single lesion, KPS score >70, and treatment with surgical resection was correlated with improved survival. Further, HER2+ patients had distinct patient and BrM characteristics.

    View details for DOI 10.1016/j.wneu.2024.09.085

    View details for PubMedID 39321918

  • Provider's exposure to diversity contributes to socioeconomic disparities in lumbar and cervical fusion outcomes. World neurosurgery: X Touponse, G., Malacon, K., Li, G., Yoseph, E., Han, S., Zygourakis, C. 2024; 23: 100382

    Abstract

    Studies report patient race, income, and education influence spinal fusion outcomes; fewer studies, however, examine the influence of provider factors such as exposure to diversity or cultural sensitivity.To examine how providers' experience with diverse patient populations affects spinal fusion outcomes.Retrospective review of 39,680 patients undergoing lumbar and cervical fusions, 2003-2021, in Clinformatics® Data Mart national database. We used the provider patient racial diversity index (pRDI)-a published metric of physician exposure to diverse patients-to divide patients into groups based their provider's category (I, II, III) where patients treated by category III providers had surgeons with the most diverse patient populations. Multivariate regression models on propensity score-matched cohorts examined the association between patient SES and provider category on post-operative outcomes.Black patients had decreased discharge home (OR 0.67; 95% CI 0.54-0.83) compared to white patients. Patients treated by category III providers had increased length of stay (Coeff. 0.62; 95% CI 0.43-0.81), charge (Coeff. 36800; 95% CI 29,200-44,400), and decreased discharge home (OR 0.90; 95% CI 0.83-0.97) compared to patients treated by category I providers. Asian patients treated by category II providers had decreased readmission (OR 0.38; 95% CI 0.14-0.96), and Black patients treated by category III providers had increased discharge home (OR 1.41; 95% CI 1.1-1.9) compared to those treated by category I providers.While our study found two specific instances of improved spine surgery outcomes for minority patients treated by providers serving diverse patient populations, we present mixed findings overall. This study serves as the foundation for future research to better understand how provider pRDI affects outcomes in patients undergoing lumbar and cervical spine surgery.

    View details for DOI 10.1016/j.wnsx.2024.100382

    View details for PubMedID 38756754

    View details for PubMedCentralID PMC11097082

  • Gender Differences in Electronic Health Record Usage Among Surgeons. JAMA network open Malacon, K., Touponse, G., Yoseph, E., Li, G., Wei, P. J., Kicielinski, K., Massie, L., Williamson, T., Han, S., Zygourakis, C. 2024; 7 (7): e2421717

    Abstract

    Understanding gender differences in electronic health record (EHR) use among surgeons is crucial for addressing potential disparities in workload, compensation, and physician well-being.To investigate gender differences in EHR usage patterns.This cross-sectional study examined data from an EHR system (Epic Signal) at a single academic hospital from January to December 2022. Participants included 224 attending surgeons with patient encounters in the outpatient setting. Statistical analysis was performed from May 2023 to April 2024.Surgeon's gender.The primary outcome variables were progress note length, documentation length, time spent in medical records, and time spent documenting patient encounters. Continuous variables were summarized with median and IQR and assessed via the Kruskal-Wallis test. Categorical variables were summarized using proportion and frequency and compared using the χ2 test. Multivariate linear regression was used with primary EHR usage variables as dependent variables and surgeon characteristics as independent variables.This study included 222 529 patient encounters by 224 attending surgeons, of whom 68 (30%) were female and 156 (70%) were male. The median (IQR) time in practice was 14.0 (7.8-24.3) years. Male surgeons had more median (IQR) appointments per month (78.3 [39.2-130.6] vs 57.8 [25.7-89.8]; P = .005) and completed more medical records per month compared with female surgeons (43.0 [21.8-103.9] vs 29.1 [15.9-48.1]; P = .006). While there was no difference in median (IQR) time spent in the EHR system per month (664.1 [301.0-1299.1] vs 635.0 [315.6-1192.0] minutes; P = .89), female surgeons spent more time logged into the system both outside of 7am to 7pm (36.4 [7.8-67.6] vs 14.1 [5.4-52.2] min/mo; P = .05) and outside of scheduled clinic hours (134.8 [58.9-310.1] vs 105.2 [40.8-214.3] min/mo; P = .05). Female surgeons spent more median (IQR) time per note (4.8 [2.6-7.1] vs 2.5 [0.9-4.2] minutes; P < .001) compared with male surgeons. Male surgeons had a higher number of median (IQR) days logged in per month (17.7 [13.8-21.3] vs 15.7 [10.7-19.7] days; P = .03). Female surgeons wrote longer median (IQR) inpatient progress notes (6025.1 [3692.1-7786.7] vs 4307.7 [2808.9-5868.4] characters/note; P = .001) and had increased outpatient document length (6321.1 [4079.9-7825.0] vs 4445.3 [2934.7-6176.7] characters/note; P < .001). Additionally, female surgeons wrote a higher fraction of the notes manually (17% vs 12%; P = .006). After using multivariable linear regression models, male gender was associated with reduced character length for both documentations (regression coefficient, -1106.9 [95% CI, -1981.5 to -232.3]; P = .01) and progress notes (regression coefficient, -1119.0 [95% CI, -1974.1 to -263.9]; P = .01). Male gender was positively associated with total hospital medical records completed (regression coefficient, 47.3 [95% CI, 28.3-66.3]; P < .001). There was no difference associated with gender for time spent in each note, time spent outside of 7 am to 7 pm, or time spent outside scheduled clinic hours.This cross-sectional study of EHR data found that female surgeons spent more time documenting patient encounters, wrote longer notes, and spent more time in the EHR system compared with male surgeons. These findings have important implications for understanding the differential burdens faced by female surgeons, including potential contributions to burnout and payment disparities.

    View details for DOI 10.1001/jamanetworkopen.2024.21717

    View details for PubMedID 39042410

    View details for PubMedCentralID PMC11267410

  • Update on Pediatric Thyroid Cancer Incidence and Mortality Trends in the United States, 2000-2018. Cancer investigation Li, G., Tai, J. W., Moon, P. K., Megwalu, U. C. 2024: 1-4

    Abstract

    Thyroid cancer is the most common endocrine malignancy in the pediatric population. A recent study has revealed a recent decline in overall US thyroid cancer incidence rates. The aim of this study is to assess whether there has been a corresponding decline in incidence rates in the pediatric population. We used the Surveillance, Epidemiology, and End Results (SEER) database to analyze the pediatric thyroid cancer incidence rate. The results demonstrate that the incidence rate of pediatric thyroid cancer continued to increase from 2000 to 2018. Future studies are needed to understand how recent changes in guidelines are affecting incidence rates.

    View details for DOI 10.1080/07357907.2024.2353313

    View details for PubMedID 38742680

  • Thyroid Cancer Incidence Among Korean Individuals: A Comparison of South Korea and the United States. The Laryngoscope Kim, D., Li, G., Moon, P. K., Ma, Y., Sim, S., Park, S. Y., Oh, M., Megwalu, U. C. 2024

    Abstract

    OBJECTIVE: To compare thyroid cancer incidence rates and trends between Korean, non-Korean Asian, and non-Hispanic White populations in the United States, and between the US Korean population and the South Korean population.METHOD: Population-based analysis of cancer incidence data. Cases of thyroid cancer diagnosed during 1999-2014 from the Korean Central Cancer Registry (KCCR) and the Surveillance, Epidemiology, and End Results (SEER) 9 detailed Asian/Pacific Islander subgroup incidence and population dataset were included. Incidence rates were obtained from the datasets, and annual percent change (APC) of the incidence rates was calculated using Joinpoint regression analysis.RESULTS: Thyroid cancer incidence rate for 1999-2014 was significantly higher for South Korea (48.05 [95% CI 47.89-48.22] per 100,000 person-years) than for the US Korean population (11.12 [95% CI 10.49-11.78] per 100,000 person-years), which was slightly higher than the Non-Korean Asian population (10.23 [95% CI 10.02-10.43] per 100,000 person-years), and slightly lower than the Non-Hispanic White population (12.78 [95% CI 12.69-12.87] per 100,000 person-years). Incidence rates in South Korea increased dramatically (average APC 17.9, 95% CI 16.0-19.9), significantly higher than the US Korean population (average APC 5.0, 95% CI 3.1-6.8), which was similar to the non-Korean Asian (average APC 2.5, 95% CI 0.9-4.2) and the non-Hispanic White (average APC 5.1, 95% CI 4.7-5.6) populations.CONCLUSIONS: South Korea's high thyroid cancer incidence rates cannot be attributed to genetic factors, but are likely due to health care system factors.LEVEL OF EVIDENCE: 3 Laryngoscope, 2024.

    View details for DOI 10.1002/lary.31490

    View details for PubMedID 38727257

  • Thoracic and Lumbar Spine Injury: Evidence-Based Diagnosis, Management, and Outcomes. The American surgeon Gomez, G. I., Li, G. Q., Valido, A. A., Stoner, A. J., Bromley-Dulfano, R. A., Sheira, D., Gonzalez, C. A., Khan, S. I., Choi, J., Zygourakis, C. C., Weiser, T. G. 2023: 31348231216479

    Abstract

    Traumatic thoracolumbar spine injuries are associated with significant morbidity and mortality. Targeted for non-spine specialist trauma surgeons, this systematic scoping review aimed to examine literature for up-to-date evidence on presentation, management, and outcomes of thoracolumbar spine injuries in adult trauma patients.This review was reported using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist. We searched four bibliographic databases: PubMed, EMBASE, Web of Science, and the Cochrane Library. Eligible studies included experimental, observational, and evidence-synthesis articles evaluating patients with thoracic, lumbar, or thoracolumbar spine injury, published in English between January 1, 2010 and January 31, 2021. Studies which focused on animals, cadavers, cohorts with N <30, and pediatric cohorts (age <18 years old), as well as case studies, abstracts, and commentaries were excluded.A total of 2501 studies were screened, of which 326 unique studies were fully text reviewed and twelve aspects of injury management were identified and discussed: injury patterns, determination of injury status and imaging options, considerations in management, and patient quality of life. We found: (1) imaging is a necessary diagnostic tool, (2) no consensus exists for preferred injury characterization scoring systems, (3) operative management should be considered for unstable fractures, decompression, and deformity, and (4) certain patients experience significant burden following injury.In this systematic scoping review, we present the most up-to-date information regarding the management of traumatic thoracolumbar spine injuries. This allows non-specialist trauma surgeons to become more familiar with thoracolumbar spine injuries in trauma patients and provides a framework for their management.

    View details for DOI 10.1177/00031348231216479

    View details for PubMedID 37983195

  • Immunosuppression in Isocitrate Dehydrogenase Mutated Acute Myeloid Leukemia Tai, J. W., Li, G., Tanaka, K., Gopakumar, J., Zhou, C., Linde, M., Villar-Prados, A., Rangavajhula, A. S., Trotman-Grant, A. C., Landberg, N., Fan, A. C., Mannis, G., Zhang, T. Y. AMER SOC HEMATOLOGY. 2023

    View details for DOI 10.1182/blood-2023-187981

    View details for Web of Science ID 001159306705096

  • Socioeconomic Influence on Cervical Fusion Outcomes. Clinical spine surgery Touponse, G., Theologitis, M., Beach, I., Rangwalla, T., Li, G., Zygourakis, C. 2023

    Abstract

    A retrospective observational study.The aim of this study was to compare postoperative outcomes following cervical fusion based on socioeconomic status (SES) variables including race, education, net worth, and homeownership status.Previous studies have demonstrated the effects of patient race and income on outcomes following cervical fusion procedures. However, no study to date has comprehensively examined the impact of multiple SES variables. We hypothesized that race, education, net worth, and homeownership influence important outcomes following cervical fusion.Optum's de-identified Clinformatics Data Mart (CDM) database was queried for patients undergoing first-time inpatient cervical fusion from 2003 to 2021. Patient demographics, SES variables, and the Charlson comorbidity index were obtained. Primary outcomes were hospital length of stay and 30-day rates of reoperation, readmission, and postoperative complications. Secondary outcomes included postoperative emergency room visits, discharge status, and total hospital charges.A total of 111,914 patients underwent cervical spinal fusion from 2003 to 2021. Multivariate analysis revealed that after controlling for age, sex, and Charlson comorbidity index, Black race was associated with a higher rate of 30-day readmissions [odds ratio (OR): 1.11, 95% CI: 1.03-1.20]. Lower net worth (vs. >$500K) and renting (vs. owning a home) were significantly associated with both higher rates of 30-day readmissions (OR: 1.29, 95% CI: 1.17-1.41; OR: 1.34, 95% CI: 1.22-1.49), and emergency room visits (OR: 1.29, 95% CI: 1.18-1.42; OR: 1.11, 95% CI: 1.00-1.23). Lower net worth (vs. >$500K) was also associated with increased complications (OR: 1.22, 95% CI: 1.14-1.31).Socioeconomic variables, including patient race, education, and net worth, influence postoperative metrics in cervical spinal fusion surgery. Future studies should focus on developing and implementing targeted interventions based on patient SES to reduce disparity.

    View details for DOI 10.1097/BSD.0000000000001533

    View details for PubMedID 37691156

  • Socioeconomic Effects on Lumbar Fusion Outcomes. Neurosurgery Touponse, G., Li, G., Rangwalla, T., Beach, I., Zygourakis, C. 2023

    Abstract

    BACKGROUND: Recent studies suggest that socioeconomic status (SES) influences outcomes after spinal fusion. The influence of SES on postoperative outcomes is increasingly relevant as rates of lumbar fusion rise.OBJECTIVE: To determine the influence of SES variables including race, education, net worth, and homeownership on postoperative outcomes.METHODS: Optum's deidentified Clinformatics Data Mart Database was used to conduct a retrospective review of SES variables for patients undergoing first-time, inpatient lumbar fusion from 2003 to 2021. Primary outcomes included hospital length of stay (LOS) and 30-day reoperation, readmission, and postoperative complication rates. Secondary outcomes included postoperative emergency room visits, discharge status, and total hospital charges.RESULTS: In total, 217204 patients were identified. On multivariate analysis, Asian, Black, and Hispanic races were associated with increased LOS (Coeff. [coefficient] 0.92, 95% CI 0.68-1.15; Coeff. 0.61, 95% CI 0.51-0.71; Coeff. 0.43, 95% CI 0.32-0.55). Less than 12th grade education (vs greater than a bachelor's degree) was associated with increased odds of reoperation (OR [odds ratio] 1.88, 95% CI 1.03-3.42). Decreased net worth was associated with increased odds of readmission (OR 1.32, 95% CI 1.25-1.40) and complication (OR 1.14, 95% CI 1.10-1.20). Renting a home (vs homeownership) was associated with increased LOS, readmissions, and total charges (Coeff. 0.30, 95% CI 0.17-0.43; OR 1.19, 95% CI 1.11-1.30; Coeff. 13200, 95% CI 9000-17000).CONCLUSION: Black race, less than 12th grade education, <$25K net worth, and lack of homeownership were associated with poorer postoperative outcomes and increased costs. Increasing perioperative support for patients with these sociodemographic risk factors may improve postoperative outcomes.

    View details for DOI 10.1227/neu.0000000000002322

    View details for PubMedID 36606803

  • 5-Aminolevulinic Acid Imaging of Malignant Glioma. Surgical oncology clinics of North America Li, G., Rodrigues, A., Kim, L., Garcia, C., Jain, S., Zhang, M., Hayden-Gephart, M. 2022; 31 (4): 581-593

    Abstract

    High-grade glioma is the most common malignant primary brain tumor in adults. Glioma infiltration renders it difficult to treat and likely to recur. Increasing the extent of resection has been associated with improving progression-free survival and overall survival by several months. The introduction of 5-aminolevulinic acid (5-ALA) fluorescence-guided surgery has allowed surgeons to better differentiate between neoplastic tissue and normal tissue, thus achieving greater extent of resection. The development of new intraoperative imaging modalities in combination with 5-ALA may provide additional benefits for glioma patients.

    View details for DOI 10.1016/j.soc.2022.06.002

    View details for PubMedID 36243495

  • Socioeconomic disparities in brain metastasis survival and treatment: a population-based study. World neurosurgery Rodrigues, A., Li, G., Bhambhvani, H., Hayden-Gephart, M. 2021

    Abstract

    INTRODUCTION: In the present study, we utilized a validated socioeconomic status (SES) index and population-based registry to identify and quantify the impact of SES on access to treatment and overall survival for patients diagnosed with synchronous brain metastases (BM).METHODS: The SEER was used to extract all patients between 2010 and 2016 with BM at initial presentation. SES was stratified into tertiles and quintiles using the validated Yost index. Multivariable logistic regressions were used to evaluate the impact of demographic, tumor, and socioeconomic covariates on receipt of radio- and chemotherapy. Kaplan-Meier curves were used to estimate survival.RESULTS: Between 2010-2016, 35,595 patients presented with brain metastases at the time of primary cancer diagnosis. Most patients received radiation and/or chemotherapy as part of the initial course of their treatment; 71.6% (n=25,484) were irradiated while 54.4% (n=19,371) received chemotherapy and 44.9% (n=15,984) received chemoradiation. Patients in the highest Yost tertile and quintile experienced longer overall survival (p < 0.001). Additionally, multivariable logistic regression revealed that the lowest Yost quintile was significantly less likely to receive either radiation (adjusted OR (aOR): 0.82; 95% CI: 0.75-0.89; p<0.001) or chemotherapy (aOR: 0.62; 95% CI: 0.58-0.67; p<0.001).CONCLUSIONS: In a large, population-based analysis of brain metastasis patients, we found significant differences in treatment access and mild survival differences along socioeconomic strata. More specifically, patients in lower SES tiers suffered worse outcomes and received radiation and chemotherapy less frequently than patients in higher tiers, even after accounting for other tumor- and demographic-related information.

    View details for DOI 10.1016/j.wneu.2021.11.036

    View details for PubMedID 34785360

  • High-quality neurosurgeon communication and visualization during telemedicine encounters improves patient satisfaction Journal of Clinical Neuroscience Rodrigues, A., Li, G., Zhang, M., Jin, M., Hayden-Gephart, M. 2021; 94: 18-23

    View details for DOI 10.1016/j.jocn.2021.09.013