- pancreatic cancer
- gastric cancer
- esophageal cancer
- Barrett's Esophagus
- colon cancer
- gastrointestinal cancer
- intestinal metaplasia
- endoscopic ultrasound
Clinical Instructor, University of California, Irvine (2006 - 2007)
Chairperson, EUS/MRI/Cross-sectional Imaging section, American Gastroenterological Association (2013 - 2014)
Chairperson, Annual Scientific Program Committee (EUS section), American Society of Gastrointestinal Endoscopy (2012 - 2013)
Director of Endoscopic Ultrasound, Stanford University School of Medicine (2010 - Present)
Honors & Awards
Howard Hughes Medical Institiute Research Fellow, Harvard Med School / Massachusetts General Hospital (1997-1998)
Most Promising Young Investigator's Award, 5th Congress of the International Xenotransplantation Association (1999)
Distinction in Transplant Immunology Research, Albert Einstein College of Medicine (2000)
Fellowship:University of California Irvine Medical Center (2007) CA
Board Certification: Gastroenterology, American Board of Internal Medicine (2006)
Fellowship:California Pacific Medical Center (2006) CA
Residency:California Pacific Medical Center (2003) CA
Internship:California Pacific Medical Center (2001) CA
Medical Education:Albert Einstein College of Medicine (2000) NY
MD, UC Irvine, Advanced Endoscopy and Endo Ultrasound (EUS) (2007)
Research Fellowship, Harvard/Mass General Hospital, Immunology (1999)
B.S., MIT, Molecular Biology (1995)
Current Research and Scholarly Interests
Dr. Chen's research focus includes various advanced therapeutic endoscopic procedures with focus on premalignant and malignant gastrointestinal diseases. Specifically, she is interested in early detection and treatment of pancreatic-biliary and gastrointestinal diseases utilizing interventional procedures such as endoscopic ultrasound, radiofrequency and cryoablation therapy, confocal microscopy, and small bowel enteroscopy.
- Locally Advanced Gastric Cancer Complicated by Mesenteric Invasion and Intestinal Malrotation DIGESTIVE DISEASES AND SCIENCES 2014; 59 (2): 267-269
Outcomes of repeat colonoscopy in patients with polyps referred for surgery without biopsy-proven cancer
2014; 79 (1): 101-107
Despite advances in endoscopic treatment, many colonic adenomas are still referred for surgical resection. There is a paucity of data on the suitability of these lesions for endoscopic treatment.To analyze the results of routine repeat colonoscopy in patients referred for surgical resection of colon polyps without biopsy-proven cancer.Retrospective review.University hospital.Patients referred to a colorectal surgeon for surgical resection of a polyp without biopsy-proven cancer.Repeat colonoscopy.The rate of successful endoscopic treatment.There were 38 lesions in 36 patients; 71% of the lesions were noncancerous and were successfully treated endoscopically. In 26% of the lesions, previous removal was attempted by the referring physician but was unsuccessful. The adenoma recurrence rate was 50%, but all recurrences were treated endoscopically and none were cancerous. Two patients were admitted for overnight observation. There were no major adverse events.Single center, retrospective.In the absence of biopsy-proven invasive cancer, it is appropriate to reevaluate patients referred for surgical resection by repeat colonoscopy at an expert center.
View details for DOI 10.1016/j.gie.2013.06.034
View details for Web of Science ID 000328736700018
View details for PubMedID 23916398
Metabolomic-derived novel cyst fluid biomarkers for pancreatic cysts: glucose and kynurenine.
2013; 78 (2): 295-302 e2
BACKGROUND: Better pancreatic cyst fluid biomarkers are needed. OBJECTIVE: To determine whether metabolomic profiling of pancreatic cyst fluid would yield clinically useful cyst fluid biomarkers. DESIGN: Retrospective study. SETTING: Tertiary-care referral center. PATIENTS: Two independent cohorts of patients (n = 26 and n = 19) with histologically defined pancreatic cysts. INTERVENTION: Exploratory analysis for differentially expressed metabolites between (1) nonmucinous and mucinous cysts and (2) malignant and premalignant cysts was performed in the first cohort. With the second cohort, a validation analysis of promising identified metabolites was performed. MAIN OUTCOME MEASUREMENTS: Identification of differentially expressed metabolites between clinically relevant cyst categories and their diagnostic performance (receiver operating characteristic [ROC] curve). RESULTS: Two metabolites had diagnostic significance-glucose and kynurenine. Metabolomic abundances for both were significantly lower in mucinous cysts compared with nonmucinous cysts in both cohorts (glucose first cohort P = .002, validation P = .006; and kynurenine first cohort P = .002, validation P = .002). The ROC curve for glucose was 0.92 (95% confidence interval [CI], 0.81-1.00) and 0.88 (95% CI, 0.72-1.00) in the first and validation cohorts, respectively. The ROC for kynurenine was 0.94 (95% CI, 0.81-1.00) and 0.92 (95% CI, 0.76-1.00) in the first and validation cohorts, respectively. Neither could differentiate premalignant from malignant cysts. Glucose and kynurenine levels were significantly elevated for serous cystadenomas in both cohorts. LIMITATIONS: Small sample sizes. CONCLUSION: Metabolomic profiling identified glucose and kynurenine to have potential clinical utility for differentiating mucinous from nonmucinous pancreatic cysts. These markers also may diagnose serous cystadenomas.
View details for DOI 10.1016/j.gie.2013.02.037
View details for PubMedID 23566642
- Metabolomic-derived novel cyst fluid biomarkers for pancreatic cysts: glucose and kynurenine GASTROINTESTINAL ENDOSCOPY 2013; 78 (2): 295-?
Endoscopic management of nonlifting colon polyps.
Diagnostic and therapeutic endoscopy
2013; 2013: 412936-?
Background and Study Aims. The nonlifting polyp sign of invasive colon cancer is considered highly sensitive and specific for cancer extending beyond the mid-submucosa. However, prior interventions can cause adenomas to become nonlifting due to fibrosis. It is unclear whether nonlifting adenomas can be successfully treated endoscopically. The aim of this study was to evaluate outcomes in a referral practice incorporating a standardized protocol of attempted endoscopic resection of nonlifting lesions previously treated by biopsy, polypectomy, surgery, or tattoo placement. Patients and Methods. Retrospective review of patients undergoing colonoscopy by one endoscopist at two hospitals found to have nonlifting lesions from prior interventions. Lesions with biopsy proven invasive cancer or definite endoscopic features of invasive cancer were excluded. Lesions ? 8?mm were routinely injected with saline prior to attempted endoscopic resection. Polypectomy was performed using a stiff snare, followed by argon plasma coagulation (APC) if necessary. Results. 26 patients each had a single nonlifting lesion with a history of prior intervention. Endoscopic resection was completed in 25 (96%). 22 required snare resection and APC. 1 patient had invasive cancer and was referred for surgery. The recurrence rate on follow-up colonoscopy was 26%. All of the recurrences were successfully treated endoscopically. There was 1 postprocedure bleed (4%), no perforations, and no other complications. Conclusions. The majority of adenomas that are nonlifting after prior interventions can be treated successfully and safely by a combination of piecemeal polypectomy and ablation. Although recurrence rates are high at 26%, these too can be successfully treated endoscopically.
View details for DOI 10.1155/2013/412936
View details for PubMedID 23761952
Pancreatic Neuroendocrine Tumors: Radiographic Calcifications Correlate with Grade and Metastasis
ANNALS OF SURGICAL ONCOLOGY
2012; 19 (7): 2295-2303
Studies to identify preoperative prognostic variables for pancreatic neuroendocrine tumor (PNET) have been inconclusive. Specifically, the prevalence and prognostic significance of radiographic calcifications in these tumors remains unclear.From 1998 to 2009, a total of 110 patients with well-differentiated PNET underwent surgical resection at our institution. Synchronous liver metastases present in 31 patients (28%) were addressed surgically with curative intent. Patients with high-grade PNET were excluded. The presence of calcifications in the primary tumor on preoperative computed tomography was recorded and correlated with clinicopathologic variables and overall survival.Calcifications were present in 16% of patients and were more common in gastrinomas and glucagonomas (50%), but never encountered in insulinomas. Calcified tumors were larger (median size 4.5 vs. 2.3 cm, P=0.04) and more commonly associated with lymph node metastasis (75 vs. 35%, P=0.01), synchronous liver metastasis (62 vs. 21%, P<0.01), and intermediate tumor grade (80 vs. 31%, P<0.01). On multivariate analysis of factors available preoperatively, calcifications (P=0.01) and size (P<0.01) remained independent predictors of lymph node metastasis. Overall survival after resection was significantly worse in the presence of synchronous liver metastasis (5-year, 64 vs. 86%, P=0.04), but not in the presence of radiographic calcifications.Calcifications on preoperative computed tomography correlate with intermediate grade and lymph node metastasis in well-differentiated PNET. This information is available preoperatively and supports the routine dissection of regional lymph nodes through formal pancreatectomy rather than enucleation in calcified PNET.
View details for DOI 10.1245/s10434-012-2305-7
View details for Web of Science ID 000305558000030
View details for PubMedID 22396008
Endoscopic mucosal resection with an over-the-counter hyaluronate preparation
2012; 75 (5): 1040-1044
Hyaluronic acid (HA) provides a long-lasting and distinct mucosal elevation for EMR, but expense and inconvenience have limited its adoption.To evaluate the safety and efficacy of an over-the-counter 0.15% HA preparation for EMR.Retrospective study.Veterans Administration Hospital and university hospital.30 patients with a total of 32 colonic lesions and 1 duodenal lesion.EMR by using HA.En bloc resection rate and complications.EMR was successful in all cases. En bloc resection was achieved in 26 of the 28 lesions up to 25 mm in diameter. Two lesions, both with fibrosis from prior attempted resection, had trace residual tissue necessitating cauterization with argon plasma. Five lesions measuring 30 mm to 60 mm all required piecemeal resection. There was one complication, a postpolypectomy bleed.Small number of patients and retrospective design.EMR may be performed safely and effectively by using an inexpensive, over-the-counter 0.15% HA preparation. Further studies are needed to verify the results of this study and to compare the safety and efficacy of this HA preparation with saline solution.
View details for DOI 10.1016/j.gie.2012.01.010
View details for Web of Science ID 000303277400016
View details for PubMedID 22381528
Diagnostic accuracy of cyst fluid amphiregulin in pancreatic cysts
Accurate tests to diagnose adenocarcinoma and high-grade dysplasia among mucinous pancreatic cysts are clinically needed. This study evaluated the diagnostic utility of amphiregulin (AREG) as a pancreatic cyst fluid biomarker to differentiate non-mucinous, benign mucinous, and malignant mucinous cysts.A single-center retrospective study to evaluate AREG levels in pancreatic cyst fluid by ELISA from 33 patients with a histological gold standard was performed.Among the cyst fluid samples, the median (IQR) AREG levels for non-mucinous (n = 6), benign mucinous (n = 15), and cancerous cysts (n = 15) were 85 pg/ml (47-168), 63 pg/ml (30-847), and 986 pg/ml (417-3160), respectively. A significant difference between benign mucinous and malignant mucinous cysts was observed (p = 0.025). AREG levels greater than 300 pg/ml possessed a diagnostic accuracy for cancer or high-grade dysplasia of 78% (sensitivity 83%, specificity 73%).Cyst fluid AREG levels are significantly higher in cancerous and high-grade dysplastic cysts compared to benign mucinous cysts. Thus AREG exhibits potential clinical utility in the evaluation of pancreatic cysts.
View details for DOI 10.1186/1471-230X-12-15
View details for Web of Science ID 000301923400002
View details for PubMedID 22333441
Cryotherapy for Barrett's esophagus: Who, how, and why?
Gastrointestinal endoscopy clinics of North America
2011; 21 (1): 111-118
Cryotherapy is a noncontact ablation method that has long been used clinically in the treatment of a wide variety of malignant and premalignant diseases. The relative ease of use and unique mechanisms of cellular destruction make cryotherapy particularly attractive for the eradication of dysplastic Barrett's esophagus. Currently, liquid nitrogen and carbon dioxide are the most common cryogens used. Preliminary data with these agents have shown high efficacy in the reversal of dysplastic Barrett mucosa and excellent safety profiles. Intense investigation on cryotherapy ablation of Barrett's esophagus is ongoing.
View details for DOI 10.1016/j.giec.2010.09.007
View details for PubMedID 21112501
- Suppurative (Phlegmonous) Gastritis Presenting as a Gastric Mass DIGESTIVE DISEASES AND SCIENCES 2010; 55 (1): 11-13
Double balloon enteroscopy detects small bowel mass lesions missed by capsule endoscopy
DIGESTIVE DISEASES AND SCIENCES
2008; 53 (8): 2140-2143
Small bowel mass lesions (SBML) are a relatively common cause of obscure gastrointestinal bleeding (OGIB). Their detection has been limited by the inability to endoscopically examine the entire small intestine. This has changed with the introduction of capsule endoscopy (CE) and double balloon enteroscopy (DBE) into clinical practice.To evaluate the detection of SBML by DBE and CE in patients with OGIB who were found to have SBML by DBE and underwent both procedures.A retrospective review of a prospectively collected database of all patients undergoing DBE for OGIB at seven North American tertiary centers was performed. Those patients who were found to have SBML as a cause of their OGIB were further analyzed.During an 18 month period, 183 patients underwent DBE for OGIB. A small bowel mass lesion was identified in 18 patients. Of these, 15 patients had prior CE. Capsule endoscopy identified the mass lesion in five patients; fresh luminal blood with no underlying lesion in seven patients, and non-specific erythema in three patients. Capsule endoscopy failed to identify all four cases of primary small bowel adenocarcinoma.Double balloon enteroscopy detects small bowel mass lesions responsible for OGIB that are missed by CE. Additional endoscopic evaluation of the small bowel by DBE or intraoperative enteroscopy should be performed in patients with ongoing OGIB and negative or non-specific findings on CE.
View details for DOI 10.1007/s10620-007-0110-0
View details for Web of Science ID 000257328000018
View details for PubMedID 18270840
- Predictive Value of Pancreatic Ductal Dilation on Endoscopic Ultrasound Diagnosis of Pancreatic Cancer Gastrointestinal Endoscopy 2007; 65 (5): AB298
What is the learning curve associated with double-balloon enteroscopy? Technical details and early experience in 6 US tertiary care centers
2006; 64 (5): 740-750
Performance parameters for double-balloon enteroscopy (DBE) have not been described.To determine the learning curve for DBE.Prospective cohort study.Six U.S. tertiary centers.A total of 188 subjects undergoing 237 DBE procedures; 130 (69%) with obscure GI bleeding.Performance parameters from each center's initial 10 cases were compared to the subsequent examinations.Exam duration, depth of insertion, and findings on DBE examination.DBE was introduced by mouth in 149 (63%) cases, by rectum in 77 (33%) cases, and through a stoma in 6 (2.5%) patients. The mean (+/-SD) duration was 109.1 +/- 44.6 minutes for the first 10 cases and 92.4 +/- 37.6 minutes for subsequent cases (P = .005) but did not change for rectal DBE procedures. There was no change in mean depth of insertion, but the mean fluoroscopy time declined significantly (P = .025). Diagnostic or therapeutic maneuvers were performed in 64% of cases; DBE led to a diagnosis in 81 (43%) patients. A total of 78% of patients had prior capsule endoscopy (CE) with significant agreement between DBE and CE (kappa = 0.74). One perforation occurred (0.4%). Per-rectal cases failed to reach the small bowel in 24 (31%) cases.All patients did not undergo initial CE. The therapeutic DBE scope was not available for the initial 8 months of the study.There was a significant decline in overall procedural time and fluoroscopy time after the initial 10 DBE cases. There was no improvement in performance parameters when DBE was performed via the rectal approach despite increased, but limited, operator experience.
View details for DOI 10.1016/j.gie.2006.05.022
View details for Web of Science ID 000241634300015
View details for PubMedID 17055868
- Porcine stem cell factor facilitates long-lasting porcine hematopoietic engraftment in murine recipients ELSEVIER SCIENCE INC. 2000: 1047-1047
Porcine stem cell engraftment and seeding of murine thymus with class II+ cells in mice expressing porcine cytokines - toward tolerance induction across discordant xenogeneic barriers
2000; 69 (12): 2484-2490
Mixed hematopoietic chimerism is a reliable means of tolerance induction, but its utility has not been demonstrated in discordant xenogeneic combinations because of the difficulty in achieving lasting hematopoietic engraftment. Miniature swine are likely to be suitable organ donors for humans. To evaluate the ability of mixed chimerism to induce swine-specific tolerance in widely disparate xenogeneic recipients, this study aimed to achieve long-lasting chimerism in a pig to mouse combination.Immunodeficient transgenic mice were developed by crossing transgenic founders carrying porcine interleukin-3, granulocyte macrophage-colony stimulating factor, and stem cell factor genes with severe combined immunodeficient mice or non-obese diabetic/severe combined immunodeficient mice. Swine bone marrow transplantation was performed in these mice, and porcine chimerism was followed for 20 weeks.Whereas swine cells became undetectable in all non-Tg littermates by 7 weeks, high levels of porcine hematopoietic chimerism, including the presence of porcine class II+ cells in the host thymus were maintained in Tg mice for >20 weeks. Colony-forming assays revealed the presence of large numbers of swine hematopoietic progenitor cells in the marrow of these mice at 20 weeks after bone marrow transplantation.These transgenic mice demonstrate for the first time that spontaneous migration of marrow donor antigen-presenting cells to an intact recipient thymus can occur and that porcine stem cells can persist in this highly disparate species combination. These data therefore support the feasibility of the eventual goal of tolerance induction by mixed chimerism in discordant xenogeneic combinations.
View details for Web of Science ID 000088238700005
View details for PubMedID 10910267
Development and analysis of transgenic mice expressing porcine hematopoietic cytokines: a model for achieving durable porcine hematopoietic chimerism across an extensive xenogeneic barrier
2000; 7 (1): 58-64
The capacity of mixed hematopoietic chimerism to induce tolerance has not been demonstrated in discordant xenogeneic species combinations because of the difficulty in achieving lasting hematopoietic engraftment. In an effort to create a model of long-lasting disparate xenogeneic hematopoietic chimerism, we have developed transgenic (Tg) mice carrying porcine cytokines. Three lines of Tg mice were generated: one carrying porcine IL-3 and GM-CSF genes only (termed IL/GM) and the remaining two lines carrying in addition, the soluble SCF gene (termed IL/GM/sS) or membrane-bound SCF gene (termed IL/GM/mS). Sera from mice with IL/GM and IL/GM/sS transgenes markedly stimulated the proliferation of swine marrow cells in vitro. However, proliferation of swine marrow cells was not induced in cultures containing IL/GM/mS sera. Consistent with these observations, ELISA assays revealed detectable levels of porcine cytokines in the sera of IL/ GM and IL/GM/sS, but not in sera of IL/GM/mS Tg mice. Marrow stromal cells prepared from all three kinds of Tg mice, but not those from non-Tg littermates, were capable of supporting the growth of porcine hematopoietic cells in vitro. Immunodeficient Tg mice were generated by crossing Tg founders with C.B-17 SCID mice for five generations. All Tg immunodeficient mice showed improved porcine hematopoietic engraftment compared with non-Tg controls. These Tg mice provide a useful model system for studying porcine hematopoietic stem cells, and for evaluating the feasibility of donor-specific tolerance induction by mixed chimerism across highly disparate xenogeneic barriers.
View details for Web of Science ID 000086912800008
View details for PubMedID 10809058
Role of antibody-independent complement activation in rejection of porcine bone marrow cells in mice
2000; 69 (1): 163-165
Although complement activation has been shown to be important in the rejection of solid organs in some xenogeneic species combinations, its role in the rejection of xenogeneic marrow engraftment is unknown.The effect of complement depletion with cobra venom factor on porcine bone marrow cell (BMC) engraftment was examined in 3 Gy-irradiated C.B-17 severe combined immunodeficiency mice receiving 10(8) pig BMC.At 26 days after transplantation, the percentages of swine class I+, myeloid, and CD2+ cells in marrow, spleen, and peripheral blood, and the numbers of porcine myeloid progenitor cells in marrow, were increased in cobra venom factor-treated recipients compared with simultaneous control recipients. Consistent with the in vivo results, preheating serum (56 degrees C for 30 min) reduced the inhibitory effect of severe combined immunodeficiency mouse serum on the proliferation of pig BMC in vitro.Murine complement is capable of resisting xenogeneic hematopoietic engraftment through an antibody-independent mechanism.
View details for Web of Science ID 000084860100027
View details for PubMedID 10653396
Routine myocardial revascularization with the radial artery: A multicenter experience
JOURNAL OF CARDIAC SURGERY
1998; 13 (5): 318-327
Current literature documents use of the radial artery (RA) for myocardial revascularization only as an alternative conduit in cases where the saphenous veins have been previously harvested or are unsuitable for use. Large-scale routine clinical use of the RA as the conduit of choice has not been reported.This prospective study evaluated the harvest of the RA from 933 patients and the subsequent use of the conduit as a preferred coronary artery bypass graft second only to the left internal thoracic artery in 930 of these patients.Unilateral RA harvest was performed in 786 patients and 147 patients had bilateral RA harvest. A total of 1080 RAs were harvested; 214 (19.8%) originated from the dominant forearm. There was a mean of 3.30+/-0.93 grafts per patient of which 2.43+/-0.83 were arterial grafts. The mean number of RA grafts was 1.43+/-0.53. Operative mortality was 2.3% with none due to the RA graft(s). There was no ischemia nor motor dysfunction in the operated hands. Thirty-two (3.4%) patients experienced transient thenar dysesthesia that resolved in 1 day to 6 weeks.Our results demonstrate that routine total or near total arterial myocardial revascularization may be achieved safely and effectively with the use of one or both RAs in conjunction with the internal thoracic artery.
View details for Web of Science ID 000081809100002
View details for PubMedID 10440646