Clinical Focus

  • Internal Medicine
  • Advanced Interventional Endoscopy
  • Gastroenterology

Academic Appointments

Honors & Awards

  • Colorectal Cancer Prevention Award, American College of Gastroenterology (October 2013)
  • Sterling Fellow Award, The University of Texas Medical School at Houston (June 2013)

Professional Education

  • Medical Education:N H L Municipal Medicine College Gujarat University (2004) India
  • Fellowship:University of Texas at Houston (2013) TX
  • Board Certification: Internal Medicine, American Board of Internal Medicine (2010)
  • Residency:University of Texas at Houston (2010) TX
  • Internship:University of Texas at Houston (2008) TX


Journal Articles

  • Photodynamic therapy vs radiofrequency ablation for Barrett's dysplasia: Efficacy, safety and cost-comparison WORLD JOURNAL OF GASTROENTEROLOGY Ertan, A., Zaheer, I., Correa, A. M., Thosani, N., Blackmon, S. H. 2013; 19 (41): 7106-7113


    To compare effectiveness, safety, and cost of photodynamic therapy (PDT) and radiofrequency ablation (RFA) in treatment of Barrett's dysplasia (BD).Consecutive case series of patients undergoing either PDT or RFA treatment at single center by a single investigator were compared. Thirty-three patients with high-grade dysplasia (HGD) had treatment with porfimer sodium photosensitzer and 630 nm laser (130 J/cm), with maximum of 3 treatment sessions. Fifty-three patients with BD (47 with low-grade dysplasia -LGD, 6 with HGD) had step-wise circumferential and focal ablation using the HALO system with maximum of 4 treatment sessions. Both groups received proton pump inhibitors twice daily. Endoscopic biopsies were acquired at 2 and 12 mo after enrollment, with 4-quadrant biopsies every 1 cm of the original BE extent. A complete histological resolution response of BD (CR-D) was defined as all biopsies at the last endoscopy session negative for BD. Fisher's exact test was used to assess differences between the two study groups for primary outcomes. For all outcomes, a two-sided P value of less than 0.05 was considered to indicate statistical significance.Thirty (91%) PDT patients and 39 (74%) RFA were men (P = 0.05). The mean age was 70.7 ± 12.2 and 65.4 ± 12.7 (P = 0.10) year and mean length of BE was 5.4 ± 3.2 cm and 5.7 ± 3.2 cm (P = 0.53) for PDT and RFA patients, respectively. The CR-D was (18/33) 54.5% with PDT vs (47/53) 88.7% with RFA (P = 0.001). One patient with PDT had an esophageal perforation and was managed with non-surgical measures and no perforation was seen with RFA. PDT was five times more costly than RFA at our institution. The two groups were not randomized and had different BD grading are the limitations of the study.In our experience, RFA had higher rate of CR-D without any serious adverse events and was less costly than PDT for endoscopic treatment of BD.

    View details for DOI 10.3748/wjg.v19.i41.7106

    View details for Web of Science ID 000327068400017

    View details for PubMedID 24222954

  • Colonoscopy and Colorectal Cancer Incidence and Mortality GASTROENTEROLOGY CLINICS OF NORTH AMERICA Thosani, N., Guha, S., Singh, H. 2013; 42 (3): 619-?


    There is substantial indirect evidence for the effectiveness of colonoscopy in reducing colorectal cancer incidence and mortality. However, several recent studies have raised questions on the magnitude of effect for right-sided colorectal cancers. Well-documented variation in outcomes when colonoscopy is performed by different groups of endoscopists suggests that the recent emphasis on the quality of the procedures should lead to improved outcomes after colonoscopy including reduction in incidence and mortality due to right-sided colorectal cancers.

    View details for DOI 10.1016/j.gtc.2013.05.011

    View details for Web of Science ID 000324221500013

    View details for PubMedID 23931863

  • Pancreatic Cancer Screening: What We Do and Do Not Know CLINICAL GASTROENTEROLOGY AND HEPATOLOGY Bhutani, M. S., Thosani, N., Suzuki, R., Guha, S. 2013; 11 (6): 731-733

    View details for DOI 10.1016/j.cgh.2013.02.004

    View details for Web of Science ID 000320306400025

    View details for PubMedID 23403010

  • Reduced Risk of Colorectal Cancer With Use of Oral Bisphosphonates: A Systematic Review and Meta-Analysis JOURNAL OF CLINICAL ONCOLOGY Thosani, N., Thosani, S. N., Kumar, S., Nugent, Z., Jimenez, C., Singh, H., Guha, S. 2013; 31 (5): 623-630


    The association between oral bisphosphonate (BP) intake and colorectal cancer (CRC) risk has been investigated in several recent studies with conflicting results. We summarized the evidence from the published studies in a categorical, dose-response meta-analysis.Relevant studies were identified by a search of MEDLINE and EMBASE databases through January 15, 2012. We included studies that reported effect size estimates with 95% CIs for the association between exposure to oral BPs and risk of CRC.Three case-control studies with a total of 16,998 CRC cases and 108,197 controls and one cohort study with 94,405 individuals exposed to BPs and 283,181 unexposed to BPs were included in meta-analysis. The random effect model meta-analysis suggested reduced risk of CRC with exposure to oral BPs with pooled odds ratio (OR) of 0.87 (95% CI, 0.78 to 0.97). Significant inverse relationship was noted for 10 or more prescriptions categories, with pooled ORs of 0.71 (95% CI, 0.58 to 0.87). Similarly, the analysis for 1 to 3 years of use and more than 3 years of use of BPs suggested a significant inverse relationship, with pooled ORs of 0.76 (95% CI, 0.68 to 0.85) and 0.78 (95% CI, 0.61 to 0.99), respectively.This meta-analysis suggests that the use of oral BPs at a dose of 10 or more prescriptions or 1 or more years of duration is associated with reduced risk of CRC. Further randomized controlled trials are needed to prove this association.

    View details for DOI 10.1200/JCO.2012.42.9530

    View details for Web of Science ID 000314820400021

    View details for PubMedID 23269990

  • Diagnostic accuracy of EUS in differentiating mucosal versus submucosal invasion of superficial esophageal cancers: a systematic review and meta-analysis GASTROINTESTINAL ENDOSCOPY Thosani, N., Singh, H., Kapadia, A., Ochi, N., Lee, J. H., Ajani, J., Swisher, S. G., Hofstetter, W. L., Guha, S., Bhutani, M. S. 2012; 75 (2): 242-253


    The prognosis of esophageal cancer (EC) depends on the depth of tumor invasion and lymph node metastasis. EC limited to the mucosa (T1a) can be treated effectively with minimally invasive endoscopic therapy, whereas submucosal (T1b) EC carries relatively high risk of lymph node metastasis and requires surgical resection.To determine the diagnostic accuracy of EUS in differentiating T1a EC from T1b EC.We performed a comprehensive search of MEDLINE, SCOPUS, Cochrane, and CINAHL Plus databases to identify studies in which results of EUS-based staging of EC were compared with the results of histopathology of EMR or surgically resected esophageal lesions. DerSimonian-Laird random-effects model was used to estimate the pooled sensitivity, specificity, and likelihood ratio, and a summary receiver operating characteristic (SROC) curve was created.Meta-analysis of 19 international studies.Total of 1019 patients with superficial EC (SEC).EUS and EMR or surgical resection of SEC.Sensitivity and specificity of EUS in accurately staging SEC.The pooled sensitivity, specificity, and positive and negative likelihood ratio of EUS for T1a staging were 0.85 (95% CI, 0.82-0.88), 0.87 (95% CI, 0.84-0.90), 6.62 (95% CI, 3.61-12.12), and 0.20 (95% CI, 0.14-0.30), respectively. For T1b staging, these results were 0.86 (95% CI, 0.82-0.89), 0.86 (95% CI, 0.83-0.89), 5.13 (95% CI, 3.36-7.82), and 0.17 (95% CI, 0.09-0.30), respectively. The area under the curve was at least 0.93 for both mucosal and submucosal lesions.Heterogeneity was present among the studies.Overall EUS has good accuracy (area under the curve ≥0.93) in staging SECs. Heterogeneity among the included studies suggests that multiple factors including the location and type of lesion, method and frequency of EUS probe, and the experience of the endosonographer can affect the diagnostic accuracy of EUS.

    View details for DOI 10.1016/j.gie.2011.09.016

    View details for Web of Science ID 000299752800003

    View details for PubMedID 22115605

  • Role of EUS-FNA-Based Cytology in the Diagnosis of Mucinous Pancreatic Cystic Lesions: A Systematic Review and Meta-Analysis DIGESTIVE DISEASES AND SCIENCES Thosani, N., Thosani, S., Qiao, W., Fleming, J. B., Bhutani, M. S., Guha, S. 2010; 55 (10): 2756-2766


    Preoperative diagnosis of malignancy in pancreatic cystic lesions (PCLs) remains challenging. Most non-mucinous cystic lesions (NMCLs) are benign, but mucinous cystic lesions (MCLs) are more likely to be premalignant or malignant.The aim of this study was to assess the sensitivity, specificity, and positive and negative likelihood ratios (LRs) of EUS-FNA-based cytology in differentiating MCLs from non-mucinous PCLs.We conducted a comprehensive search of MEDLINE, SCOPUS, Cochrane, and "CINAHL Plus" databases to identify studies, in which the results of EUS-FNA-based cytology of PCLs were compared with those of surgical biopsy or surgical excision histopathology. A DerSimonian-Laird random effect model was used to estimate the pooled sensitivity, specificity, and LRs, and a summary receiver-operating characteristic (SROC) curve was constructed.We included 376 patients from 11 distinct studies who underwent EUS-FNA-based cytology and also had histopathological diagnosis. The pooled sensitivity and specificity in diagnosing MCLs were 0.63 (95% CI, 0.56-0.70) and 0.88 (95% CI, 0.83-0.93), respectively. The positive and negative LRs in diagnosing MCLs were 4.46 (95% CI, 1.21-16.43) and 0.46 (95% CI, 0.25-0.86), respectively. The area under the curve (AUC) was 0.89.EUS-FNA-based cytology has overall low sensitivity but good specificity in differentiating MCLs from NMCLs. Further research is required to improve the overall sensitivity of EUS-FNA-based cytology to diagnose MCLs while evaluating PCL.

    View details for DOI 10.1007/s10620-010-1361-8

    View details for Web of Science ID 000282093700027

    View details for PubMedID 20694512

  • Endoscopic retrograde cholangiopancreatography for suspected choledocholithiasis: Testing the current guidelines DIGESTIVE AND LIVER DISEASE Rubin, M. I., Thosani, N. C., Tanikella, R., Wolf, D. S., Fallon, M. B., Lukens, F. J. 2013; 45 (9): 744-749


    Current guidelines include an algorithm for predicting choledocholithiasis. Presence of any very strong predictor or both strong predictors confers a high (>50%) probability of choledocholithiasis. Absence of predictors confers low risk (<10%) of choledocholithiasis. Other combinations have an intermediate risk of choledocholithiasis.Determine accuracy of the proposed algorithm in predicting choledocholithiasis.Retrospective analysis of all endoscopic retrograde cholangiopancreatographies performed for suspected choledocholithiasis in 3 years in a Tertiary care hospital and a community hospital serviced by The University of Texas Health Science Center at Houston Division of Gastroenterology. Application of the guidelines, and comparing results to endoscopic retrograde cholangiopancreatography findings.A total of 1080 endoscopic retrograde cholangiopancreatographies were performed; 521 for choledocholithiasis. Most patients were Hispanic and female. Univariate analysis: presence of any very strong predictor and both strong predictors had an OR for choledocholithiasis of 3.30 and 2.36 respectively. Multivariate analysis: odds of choledocholithiasis with any very strong predictor was 2.87, and both strong predictors 3.24. Choledocholithiasis was present in 71.5%, and 41% of patients with high, and intermediate risk respectively.This study confirms the utility of clinical predictors for the diagnosis of choledocholithiasis. All of the very strong predictors and one of the strong predictors increased the odds of choledocholithiasis. Patients with high risk for choledocholithiasis had a probability of 79% of choledocholithiasis. Sensitivity and specificity of current predictors are too low to obviate the possible need of non-invasive tests to confirm or exclude choledocholithiasis in all risk groups.

    View details for DOI 10.1016/j.dld.2013.02.005

    View details for Web of Science ID 000323601900008

    View details for PubMedID 23540659

  • A heart of stone. Gastroenterology Thosani, N., Younes, M., Pan, J. 2013; 145 (1): e6-7

    View details for DOI 10.1053/j.gastro.2013.03.026

    View details for PubMedID 23727481

  • Noninvasive biomarkers for the diagnosis of steatohepatitis and advanced fibrosis in NAFLD. Biomarker research Pearce, S. G., Thosani, N. C., Pan, J. 2013; 1 (1): 7-?


    Nonalcoholic fatty liver disease (NAFLD) is the most common cause of abnormal liver enzymes in both adults and children. NAFLD has a histologic spectrum ranging from simple steatosis to nonalcoholic steatohepatitis (NASH), advanced fibrosis, and cirrhosis. It is imperative to distinguish simple steatosis from NASH since the latter has a progressive disease course and can lead to end-stage liver disease. Liver biopsy has been considered as the gold standard for the diagnosis of NASH. However, liver biopsy is invasive, costly, and can rarely cause significant morbidity (risk of morbidity, 0.06-0.35%; risk of mortality, 0.1-0.01%). Imaging studies such as ultrasonography, computed tomography, and magnetic resonance imaging have limited sensitivity in detecting steatosis and cannot distinguish steatosis from NASH. Alanine aminotransferase (ALT) has been used as a surrogate marker for liver injuries. However, ALT is not an ideal marker for either diagnosis of NAFLD or distinguishing steatosis from NASH. Better noninvasive biomarkers or panels of biomarkers that are cheaper, reliable, and reproducible are urgently needed for patients with NASH to assist in establishing diagnosis, providing risk information, and monitoring disease progression and treatment response. In this article, we plan to concisely review the current advances in the use of biomarkers for the diagnosis of NASH.

    View details for DOI 10.1186/2050-7771-1-7

    View details for PubMedID 24252302

  • Oral Bisphosphonates and Colorectal Cancer: Cumulative Dose and Duration of Use Are Important Predictors of Effect. Clinical gastroenterology and hepatology : the official clinical practice journal of the American Gastroenterological Association Thosani, N., Guha, S., Singh, H. 2013

    View details for PubMedID 23591285

  • Clinical Impact of EUS-FNA of Mediastinal Lymph Nodes in Patients with Known or Suspected Lung Cancer or Mediastinal Lymph Nodes of Unknown Etiology JOURNAL OF GASTROINTESTINAL AND LIVER DISEASES Srinivasan, R., Bhutani, M. S., Thosani, N., Saftoiu, A., Rice, D. C., Ioncica, A. M., Eapen, G. A., Gupta, P., Jaganmohan, S., Artifon, E. L., Zwischenberger, J. B. 2012; 21 (2): 145-152


    Endoscopic ultrasound guided fine needle aspiration (EUS-FNA) of mediastinal lymph nodes (LNs) has emerged as a valuable minimally invasive tool for staging. The objective of this study was to determine the accuracy of EUS-FNA of mediastinal LNs in patients with known or suspected non-small cell lung cancer (NSCLC) or with mediastinal LNs of unknown etiology and review its clinical impact.A review was performed on 107 consecutive patients. If malignant cells were identified by EUS-FNA, the result was accepted as a true positive. When cytology was non-malignant, results were compared with the final surgical pathology.Of 79 patients with known or suspected lung cancer who had mediastinal LNs, 69 patients underwent EUS-FNA. Thirty-two received a definitive diagnosis with EUS-FNA and did not undergo further workup, while 37 patients had benign (33) or non-diagnostic FNAs (4); 26 patients further underwent surgical staging. Sensitivity, specificity, and accuracy for EUS-FNA of mediastinal LNs in patients with known or suspected lung cancer was 82.35%, 100%, and 90% respectively. The negative predictive value was 80% and the positive predictive value was 100%. There were 20 patients with suspicious mediastinal LNs of uncertain etiology, with a definitive diagnosis being made using EGD/EUS-FNA in 95%.Our data supports the use of EUS-FNA in the work-up of enlarged mediastinal LNs on cross sectional imaging, thus avoiding more invasive mediastinal sampling procedures and potentially futile surgery.

    View details for Web of Science ID 000305866400008

    View details for PubMedID 22720302

  • Current use of hepatitis B immune globulin for prevention of de novo hepatitis B in recipients receiving anti-HBc-positive livers HEPATOLOGY INTERNATIONAL Pan, J., Thosani, N., Machicao, V. I., Fallon, M. B. 2011; 5 (2): 635-643


    Livers from donors positive for antibody against anti-HBc can potentially transmit de novo hepatitis B (DNH) to their recipients. Despite a good outcome, prophylaxis is usually offered to such recipients. There is no consensus on the standard prophylactic regimen and hence prophylaxis varies among different transplant centres. Nonetheless, hepatitis B immune globulin (HBIG) is considered the mainstay of such prophylaxis, either alone or in combination with an oral antiviral treatment. We aim to provide a concise review of the current use of HBIG in prevention of DNH. We also address a few important questions regarding HBIG use.

    View details for DOI 10.1007/s12072-010-9250-y

    View details for Web of Science ID 000290452500003

    View details for PubMedID 21484133

  • Molecular Pathogenesis of Intraductal Papillary Mucinous Neoplasms of the Pancreas PANCREAS Thosani, N., Dasari, C. S., Bhutani, M. S., Raimondo, M., Guha, S. 2010; 39 (8): 1129-1133


    Over the last 3 decades, there have been substantial improvements in diagnostic imaging and sampling techniques to evaluate pancreatic diseases. The modern technology has helped us to recognize premalignant conditions of pancreas including mucinous cystic neoplasms and intraductal papillary mucinous neoplasms (IPMNs). Differentiation between benign and malignant lesions and early detection of any malignant transformation in premalignant lesion are extremely important for further management decisions. Diagnostic cytology has limited sensitivity to further differentiate between benign, premalignant, and malignant lesions of the pancreas. There is limited information about the epidemiological risk factors and molecular mechanisms leading to development and further progression to malignancy of IPMNs. Several studies have shown that pancreatic juice and pancreatic tissue from the lesion can be tested for molecular markers including K-ras, p53, and p16 to differentiate between cancer and chronic inflammatory process. We review cellular signaling pathways that contribute to pathogenesis of IPMNs of the pancreas to further identify potential biomarkers and molecular targets.

    View details for DOI 10.1097/MPA.0b013e3181f66cdf

    View details for Web of Science ID 000282946600003

    View details for PubMedID 20881900

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