Sam Chen

Sam Chen
Taipei Medical University | TMU

Doctor of Philosophy

About

361
Publications
29,441
Reads
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8,488
Citations
Introduction
Research interest is disease prevention, with the emphasis on the bioinformatics, AI, and outcomes research.
Additional affiliations
March 2011 - December 2020
Taipei Medical University
Position
  • Professor (Full)
Education
September 2000 - September 2005

Publications

Publications (361)
Article
Purpose To use mammographic tumour features (imaging biomarkers) to identify and investigate breast cancers originating from the terminal ductal lobular units (TDLUs) of the breast in order to overcome the confusion arising from the current histopathology terminology, which calls cancers arising from the TDLUs either “ductal” or “lobular”. Method...
Article
Purpose To encourage and facilitate the recognition of ductal adenocarcinoma of the breast, DAB, as a distinct, invasive breast cancer subtype by describing the imaging biomarkers in detail. Methods Correlation of breast imaging biomarkers with the corresponding histopathological findings using large format technology, with additional evidence fro...
Article
Background This study is aimed at estimating the unbiased effectiveness of population-based breast cancer service screening based on case survival information alone rather than large-scale individual screening data pursuant to the intention-to-treat principle of a randomized–controlled trial. Methods A novel time-dependent switched design with two...
Preprint
Background It is important for understanding the impact of COVID-19 pandemic on the missing opportunity for the early detection of oral cancer. This study aimed to assess the impact of COVID-19 pandemic on the existing population-based oral cancer (OC) service screening program in Taiwan. Methods Before and after COVID-19 pandemic design was used...
Article
Purpose To call attention to a highly fatal breast cancer subtype arising from the major lactiferous ducts that is currently underdiagnosed as ductal carcinoma in situ (DCIS) with or without microinvasion. Method All breast cancers diagnosed at the Department of Mammography, Falun Central Hospital, Sweden, since 1977 have been classified according...
Preprint
We applied a four-state stochastic process to decipher the natural infectious process of SARS-CoV-2 superimposed with the disease axis of pre-symptomatic, asymptomatic, and symptomatic states. So doing provides new insights into how pre-symptomatic transmission and the proportion of asymptomatic cases have been affected by SARS-CoV-2 variants, NPIs...
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Facing the emerging COVID viral variants and the uneven distribution of vaccine worldwide, imported pre-symptomatic COVID-19 cases play a pivotal role in border control strategies. A stochastic disease process and computer simulation experiments with Bayesian underpinning was therefore developed to model pre-symptomatic disease progression during i...
Article
Purpose To use mammographic tumour features (imaging biomarkers) to classify breast cancer according to its apparent anatomic site of origin in the new era where tumours are found at their nonpalpable, earliest detectable phase. Method Large format, subgross, three-dimensional histopathologic images of breast cancer subtypes and their correspondin...
Article
Background/purpose The postgraduate year dentist training program (PGYD) officially implemented in 2010. This study aimed to assess PGYD trainees’ subjective satisfaction perception and objective competence performance according to different training institutions (either dental clinics or hospitals). Materials and methods A nationwide cross-sectio...
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The purpose of this research is to elucidate whether metabolic syndrome affects the rate of adoption of a new multiple cancer screening programme, based on the Diffusion of Innovation theory. The time to attend the screening programme, conducted in Keelung, Taiwan, within 10 years was assessed by innovativeness (innovators, early adaptors, early ma...
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Background This study seeks to elucidate the impact of COVID-19 on knowledge, attitude, and infection control behaviors among dentists. Methods Changes in knowledge, attitude, and infection control behaviors reported in 2020 (COVID-19 period) were compared to the historical control of the non-COVID-19 period in 2018. A proportional random sampling...
Preprint
Objectives Two kinds of epidemic surveillance models are presented for containing the spread of SARS-CoV-2 variants so as to avert and stamp out a community-acquired outbreak (CAO) with non-pharmaceutical interventions (NPIs), tests, and vaccination. Design The surveillance of domestic cluster infections transmitted from imported cases with one-we...
Article
COVID-19 pandemic has severely affected regular public health interventions including population-based cancer screening. Impacts of such screening delays on the changes in structure and screening process and the resultant long-term outcomes are unknown. It is therefore necessary to develop a systematic framework to assess theses impacts related to...
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Background Dental students have encountered changes in the teaching format amid the SARS CoV-2 pandemic. This study aims to evaluate the attitudes of dental students of one medical university toward online courses and compare them with those of non-dental students amid the SARS CoV-2 pandemic. Methods A cross-sectional survey with a self-report on...
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Although dental treatment with sedation is performed increasingly in special needs patients, data on adding midazolam to intravenous propofol sedation are very limited for this group. The purpose of this study was to identify the factors and procedure time associated with the use of intravenous sedation with propofol alone or propofol combined with...
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This community-based study aimed to elucidate whether there is a gender difference in the effect of metabolic syndrome (MetS) and its individual components on an elevated risk for incident colorectal adenoma.A prospective cohort study was conducted by enrolling 59,767 subjects aged 40 years or older between 2001 and 2009 in Keelung, Taiwan, to test...
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Background Household transmission is responsible for the subsequent outbreak of community-acquired COVID-19. The aim of this study was to elucidate the household transmission mode and to further estimate effective and basic reproductive number with and without non-pharmaceutical interventions (NPIs). Materials and Methods A total of 26 households...
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Background As Coronavirus disease 2019 (COVID-19) pandemic led to the unprecedent large-scale repeated surges of epidemics worldwide since the end of 2019, data-driven analysis to look into the duration and case load of each episode of outbreak worldwide has been motivated. Methods Using open data repository with daily infected, recovered and deat...
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Colorectal cancer(CRC) is one of the most prevalent malignancies in the Asia-Pacific region, and many countries in this region have launched population CRC service screening. In this study, CRC screening key indicators, including the FIT(fecal immunochemical test) screening rate (or participation rate) and the rate of undergoing colonoscopy after p...
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The spread of the emerging pathogen, named as SARS-CoV-2, has led to a unprecedented COVID-19 pandemic since 1918 influenza pandemic. This review first sheds light om the similarity on global transmission, surges of pandemics, and the disparity of prevention between two pandemics. Such a brief comparison also provides an insight into the potential...
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Background Cumulative data of case-fatality rates (CFR) of COVID-19 varied across countries. A forecasting model generated based on detailed information from three countries during the initial phase of pandemic showed that progression rates from pneumonia to ARDS (PRPA) varied by country and were highly associated with CFR. We aim to elucidate the...
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Rationale & objective: Hemodialysis facilities are high-risk environments for hepatitis C virus (HCV). Eliminating HCV from all dialysis facilities in a community may be achieved more effectively under a collaborative care model. Study design: Quality improvement study of multidisciplinary collaborative care teams including nephrologists, gastro...
Preprint
BACKGROUND Pre-symptomatic imported COVID-19 cases play an important role in border control strategies for containing their further spread to community outbreaks. OBJECTIVE A pre-symptomatic incubation model was proposed to develop precision screening, quarantine, and isolation strategies for containing imported COVID-19 case. METHODS The natural...
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The association between osteoporosis and periodontal disease (PD) has been revealed by previous studies, but there have been few studies on the association in younger adults. We enrolled a total of 7298 adults aged 40 to 44 who underwent PD screening between 2003 and 2008. Data on quantitative ultrasound for the measurement of bone mineral density...
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IntroductionEfficient evaluation with an early surrogate endpoint, taking into account the process of disease evolution, may not only clarify inconsistent or underpowered results but also provide a new insight into the exploration of a new antiviral therapy for treating COVID-19 patients.Methods We assessed the dynamics of COVID-19 disease spectrum...
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Background Previously, the risk of death from breast cancer was analyzed for women participating versus those not participating in the last screening examination before breast cancer diagnosis. Consecutive attendance patterns may further refine estimates. Purpose To estimate the effect of participation in successive mammographic screening examinati...
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Objective To evaluate the effect of the periodontal primary care (PPC) on the improvement of periodontal pocket depth based on a periodontist's 30‐year practice. Materials and Methods We enrolled a total of 2,894 patients who underwent periodontal basic treatment between 1987 and 2017 with 84.5% retention rate. The study population was composed of...
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Background & Aims Taiwan has launched a series of population-wide interventions on hepatocellular carcinoma (HCC) related to hepatitis B and C virus infection since 1984. It therefore provides a natural opportunity to evaluate whether the reduction of HCC incidence, to a greater extent, and the improvement of case-fatality, to a lesser extent, or v...
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Multistate statistical models are often used to characterize the complex multi-compartment progression of the disease such as cancer. However, the derivation of multistate transition kernels is often involved with the intractable convolution that requires intensive computation. Moreover, the estimation of parameters pertaining to transition kernel...
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In this perspective, we outline that a space borne gravitational wave detector network combining LISA and Taiji can be used to measure the Hubble constant with an uncertainty less than 0.5% in ten years, compared with the network of the ground based gravitational wave detectors which can measure the Hubble constant within a 2% ncertainty in the ne...
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Objective To measure the effects of faecal immunochemical test (FIT) for colorectal cancer (CRC) screening on overall and site-specific long-term effectiveness of population-based organised service screening. Design A prospective cohort study of Taiwanese nationwide biennial FIT screening was performed. A total of 5 417 699 eligible subjects were...
Article
Objective To classify interval colorectal cancers as false negatives or newly occurring cases in a biennial Fecal immunochemical test (FIT) screening program and by various interscreening intervals. Setting Data from the Taiwanese biennial colorectal cancer screening program involving FIT from 2004 to 2014 were used to estimate the incidence rate...
Chapter
This chapter first introduces the necessity of extending evidence-based colorectal cancer (CRC) screening illustrated with the stool-based screening methods into a service screening program. The concept and feature of opportunistic and organized service screening were then distinguished by the way of invitations to the targeted population eligible...
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There is a serious concern over the variation of case fatality of COVID-19 patients that reflects the preparedness of the medical care system in response to the surge of pneumonia patients. We aimed to quantify the disease spectrum of COVID-19 on which we are based to develop a key indicator on the probability of progression from pneumonia to acute...
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Evaluating the performance of serum prostate-specific antigen (PSA) test in population-based screening with receiver operating characteristics (ROC) curve often neglects the time dimension. Asymptomatic cases with negative PSA test would have been missed if sojourn time is not taken into account to allow for cases surfacing into the clinical phase....
Chapter
Health information system supporting population-based organized service screening for colorectal cancer (CRC) is critically important for delivery, surveillance, and management of screening services in order to aid health professionals improving the quality assurance and enhancing the feasibility of evaluating the screening program. Health informat...
Article
Objectives This study analyzed the role of the interleukin (IL)‐6/signal transducer and activator of transcription 3 (STAT3) pathway in dihydropyridine‐induced gingival overgrowth (DIGO) fibroblasts. Materials and methods Tissue samples were obtained through surgical dissection from five DIGO patients and five healthy individuals. Cell cultures we...
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Objectives: We aimed to assess the effect of metabolic syndrome (MetS) on incident oral potentially malignant disorder (OPMD). Design: We conducted a prospective cohort study of the Changhua community-based integrated screening (CHCIS) programme and nationwide oral cancer screening programme during the period between 2005 and 2014. Setting: CH...
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Background: To assess the impact of treatment delay on survival of oral/oropharyngeal cancer (OSCC). Methods: We followed 5743 OSCCs between 2004 and 2009 from a population-based screening program and ascertained death until the end of 2012. Results: The hazard ratios (HRs) of mortality from OSCC were 1.46 (1.30-1.65) and 1.18 (1.04-1.33) in u...
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Objective: Subjects with a positive faecal immunochemical test (FIT) have a much higher likelihood of advanced neoplasms than the general population. Whether FIT-positive subjects with negative colonoscopy should receive subsequent FIT screening remain unclear. Design: Subjects with a negative colonoscopy after positive FIT in the first screenin...
Article
Not only were social events and public facilities closed temporarily due to the coronavirus disease 2019 (COVID‐19) pandemic, but health services also were affected greatly. In this commentary, the authors discuss how the national program of mammography screening in Taiwan was affected, even without known community‐acquired transmission.
Article
Background Implementing and lifting social distancing (LSD) is an urgent global issue during the COVID-19 pandemic, particularly when the travel ban is lifted to revive international businesses and economies. However, when and whether LSD can be considered is subject to the spread of SARS-CoV-2, the recovery rate, and the case-fatality rate. It is...
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Objective Although mass eradication of Helicobacter pylori has been proposed as a means to eliminate gastric cancer, its long-term effects remain unclear. Design Mass eradication of H. pylori infection was launched in 2004 and continued until 2018 for a high-risk Taiwanese population aged 30 years or older dwelling on Matsu Islands with prevalent...
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There are few published studies that report the prevalence of intraoral anomalies for young children. The purpose of this study was to investigate the prevalence and distribution of several congenital oral and paraoral anomalies in Taiwanese children under age six. Twenty-five cities and townships were randomly sampled in different areas of Taiwan...
Article
Background & Aim The reliable method to stratify the gastric cancer risk after Helicobacter pylori eradication remains an elusive goal. Methods Mass eradication of H. pylori began in 2004 in a high‐risk population. After eradication, a screening program involving first‐stage serological tests (pepsinogen‐I, pepsinogen‐II, H. pylori immunoglobin G,...
Preprint
Full-text available
BACKGROUND Implementing and lifting social distancing (LSD) is an urgent global issue of COVID-19 pandemic particularly when the travel ban is lifted to revive international business and economics. However, when and whether LSD can be considered is subject to the spread of SARS-COV-2, the recovery rate, and case-fatality rate. It is imperative to p...
Preprint
Full-text available
Background We aimed to investigate factors associated with personal self-protection in infection control among dental care workers. Methods A cross-sectional survey with self-report questionnaire was conducted between Jan and Dec, 2018. 275 dentists and 298 dental assistants were enrolled from randomly selected dental care settings. Results Complia...
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The aim was to evaluate how the inter-screening interval affected the performance of screening by mammographic appearances. This was a Swedish retrospective screening cohort study with information on screening history and mammography features in two periods (1977–1985 and 1996–2010). The pre-clinical incidence and the mean sojourn time (MST) for sm...
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Context Easing social distancing (ESD) is a global public health issue in post-pandemic period of COVID-19 and requires a simple index for real time assessment. Objective We aimed to develop a simple index for ESD to quantify the impacts of social distancing for reducing confirmed infected cases, optimal triage and care of patients for recovery, an...
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Objectives The role of faecal haemoglobin as a colorectal cancer screening tool has been demonstrated. However, the association between the faecal haemoglobin concentration and the risk of cardiovascular disease events and deaths is still unclear. Design Cohort study design. Setting Population-based organised integrated service screening in Keelu...
Preprint
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Background: The impact of remdesivir on length of stay of hospitalization, high-risk state, and death stratified by the severity of COVID-19 at enrollment is controversial. Methods: We applied a simulated two-arm controlled study design to the data on compassionate use of remdesivir as a secondary analysis. Dynamics of risk states and death from CO...
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Background: The aim of the current study was to report a single-institution experience using breast-conserving surgery after neoadjuvant chemotherapy (NACT), focusing on the association between microscopic resection margin status and locoregional recurrence (LRR). Methods: Our institutional prospectively maintained database was reviewed to ident...
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Background: It is of paramount importance to evaluate the impact of participation in organized mammography service screening independently from changes in breast cancer treatment. This can be done by measuring the incidence of fatal breast cancer, which is based on the date of diagnosis and not on the date of death. Methods: Among 549,091 women,...
Preprint
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While the recent study on the compassionate use of remdesivir for COVID-19 patients has shown a 68% clinical improvement ⁷ it is a one-arm study that renders the evaluation of the efficacy in reducing death and the length of stay of hospitalization intractable due to a lacking of the control group. We came up with a two-arm controlled study design...
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Objectives To explain apparent differences among mammography screening services in Sweden using individual data on participation in screening and with breast cancer–specific survival as an outcome. Methods We analysed breast cancer survival data from the Swedish Cancer Register on breast cancer cases from nine Swedish counties diagnosed in women e...
Preprint
BACKGROUND Low infection and case-fatality rate has been so far observed in Taiwan. One of major success is attributed to making a better use of big data analytics in efficient contacting tracing and management and surveillance of those who required quarantine and isolation. OBJECTIVE We present here a unique application with big data analytics to...
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Full-text available
Background: Low infection and case-fatality rate has been so far observed in Taiwan. One of major success is attributed to making a better use of big data analytics in efficient contacting tracing and management and surveillance of those who required quarantine and isolation. Objective: We present here a unique application with big data analytic...
Preprint
Full-text available
Background The aim of the current study was to report a single-institution experience using breast-conserving surgery after neoadjuvant chemotherapy (NACT), focusing on the association between microscopic resection margin status and locoregional recurrence (LRR). Methods Our institutional prospectively maintained database was reviewed to identify p...
Article
Background Deep brain stimulation of subthalamic nucleus (STN-DBS) is an effective therapy for Parkinson’s disease (PD). However, cost-effectiveness analysis (CEA) is required because most patients are older adults and decision-makers must therefore consider whether the long-term effectiveness outweighs the initial cost. Method A Markov decision m...