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Amitabh Chak

Publications and source records attributed to Amitabh Chak.

At least 19 recordsLinked to original sources
PubMed2024

Molecular Analysis of Persistent and Recurrent Barrett's Esophagus in the Setting of Endoscopic Therapy.

INTRODUCTION: Early neoplastic progression of Barrett's esophagus (BE) is often treated with endoscopic therapy. Although effective, some patients are refractory to therapy or recur after apparent eradication of the BE. The goal of this study was to determine whether genomic alterations within the treated BE may be associated with persistent or recurrent disease. METHODS: We performed DNA sequencing on pre-treatment esophageal samples from 45 patients who were successfully treated by endoscopic therapy and did not recur as well as pre-treatment and post-treatment samples from 40 patients who had persistent neoplasia and 21 patients who had recurrent neoplasia. The genomic alterations were compared between groups. RESULTS: The genomic landscape was similar between all groups. Patients with persistent disease were more likely to have pre-treatment alterations involving the receptor tyrosine kinase pathway ( P = 0.01), amplifications of oncogenes ( P = 0.01), and deletions of tumor suppressor genes ( P = 0.02). These associations were no longer significant after adjusting for patient age and BE length. More than half of patients with persistent (52.5%) or recurrent (57.2%) disease showed pre-treatment and post-treatment samples that shared at least 50% of their driver mutations. DISCUSSION: Pre-treatment samples were genomically similar between those who responded to endoscopic therapy and those who had persistent or recurrent disease, suggesting there is not a strong genomic component to treatment response. Although it was expected to find shared driver mutations in pre-treatment and post-treatment samples in patients with persistent disease, the finding that an equal number of patients with recurrent disease also showed this relation suggests that many recurrences represent undetected minimal residual disease.

Humans↗
PubMed2006

Colorectal screening after polypectomy: a national survey study of primary care physicians.

BACKGROUND: Recommendations by primary care physicians for colorectal screening after polypectomy will influence rates of colonoscopy in open-access systems that do not require consultation by a gastroenterologist before colonoscopy. OBJECTIVE: To determine the surveillance recommendations of primary care physicians after polypectomy and compare them with recommendations from the U.S. Multisociety Task Force on Colorectal Cancer. DESIGN: Cross-sectional study of physicians. SETTING: United States. PARTICIPANTS: A random sample of 500 physicians from the American College of Physicians and 500 physicians from the American Academy of Family Physicians, obtained by using a mail survey. MEASUREMENTS: Physicians were asked when they would recommend repeated colonoscopy for a hypothetical 55-year-old man with no family history of colorectal cancer after the following 6 results on colonoscopy: hyperplastic polyp, one 6-mm tubular adenoma, two 6-mm tubular adenomas, one 12-mm tubulovillous adenoma, one 12-mm tubular adenoma with focal high-grade dysplasia, and no polyp but a previous tubular adenoma. RESULTS: The overall response rate was 57% (568 physicians). Of the respondents, 48% were internists and 52% were family practitioners. Sixty-one percent of respondents would survey a hyperplastic polyp in 5 years or less, 71% would survey a single tubular adenoma in 3 years or less, and 80% would survey 2 tubular adenomas in 3 years or less. LIMITATIONS: The results are based on physicians' self-reported practices from clinical vignettes and may not match actual practice. CONCLUSION: Primary care physicians recommend postpolypectomy colonoscopic surveillance more frequently than is recommended by practice guidelines, especially if the colonoscopy showed a hyperplastic polyp or a single small adenoma.

Adenoma, Villous↗
PubMed2006

Gastroesophageal reflux symptoms in patients with adenocarcinoma of the esophagus or cardia.

BACKGROUND: The efficacy of endoscopic screening for chronic gastroesophageal reflux symptoms of heartburn and regurgitation in adult subjects depends on the sensitivity of this strategy for detecting Barrett esophagus in subjects before the development of adenocarcinoma of the esophagus or cardia. The aim of the current study was to determine what proportion of patients with cancer of the esophagus or cardia would have been candidates for a screening endoscopy before their cancer diagnosis based on the presence and duration of preceding reflux symptoms. METHODS: All patients with adenocarcinoma of the esophagus, adenocarcinoma of the cardia, or long-segment Barrett esophagus presenting for endoscopy at 4 tertiary care and 2 Veterans Affairs (VA) hospitals were given a previously validated questionnaire to determine their recall of common gastroesophageal reflux symptoms. RESULTS: The study population of 375 subjects consisted primarily of 294 (78%) white men. Only 67 of 110 patients (61%) with adenocarcinoma of the esophagus and 8 of 21 patients (38%) with adenocarcinoma of the cardia recalled symptoms of heartburn or regurgitation being present for >5 years before their diagnosis of cancer. Only 40 of 110 patients (36%) with adenocarcinoma of the esophagus and 5 of 21 patients (24%) with adenocarcinoma of the cardia recalled weekly symptoms being present for >5 years before their cancer diagnosis. Of the 244 patients with Barrett esophagus, 170 (70%) recalled heartburn or regurgitation for >5 years and 89 patients (37%) recalled weekly symptoms for >5 years. CONCLUSIONS: Current practice, which uses a screening strategy of performing endoscopy in patients with >5 years of heartburn or regurgitation, can detect Barrett epithelium in only a limited proportion of those patients at risk for developing adenocarcinoma of the esophagus or adenocarcinoma of the cardia.

Adenocarcinoma↗
PubMed2006

Endoscopic ultrasonography and prognosis of esophageal cancer.

BACKGROUND & AIMS: Endoscopic ultrasonography (EUS) staging is used for management of esophageal cancer, but its effect on the outcome of patients is unknown. Our aim was to study the association of receipt of EUS and overall survival in a cohort of patients with esophageal cancer. METHODS: All persons 65 years or older who were diagnosed with esophageal cancer between January 1994 and December 1999 in the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database were identified. Relevant demographic, cancer-specific information and EUS procedural information were extracted. RESULTS: Two thousand eight hundred thirty patients with esophageal cancer (48% squamous cell cancer) were eligible for analysis. Only 303 (10.7%) patients underwent a EUS examination. Patients who had EUS evaluation were more likely to undergo esophageal resection (21.1% vs 14.7%, P = .01) and more likely to have received adjuvant therapy (11.2% vs 6.7%, P = .008). When adjusted for age at diagnosis, race, gender, comorbidity, histology, and tumor stage, receipt of EUS was associated with a reduced risk of death (relative hazard, 0.594; 95% confidence interval, 0.52-0.68; P = .001). CONCLUSIONS: Undergoing EUS in patients with esophageal cancer is independently associated with improved survival, possibly because of improved stage-appropriate management such as use of adjuvant therapy and surgical resection.

Adenocarcinoma↗
PubMed2006

Primary care physician attitudes toward endoscopic screening for GERD symptoms and unsedated esophagoscopy.

BACKGROUND: Current guidelines recommend consideration of screening patients with chronic GERD for Barrett's esophagus (BE). Unsedated esophagoscopy (UE) is a less costly alternative to standard EGD for identifying BE. The aim of this study was to determine the indications for EGD referral, the barriers to screening, and the interest in performing UE. METHODS: A one-page survey was mailed to a random sample of 500 family practitioners and 500 internists. This sample was obtained from the American Academy of Family Physicians and American Society of Internal Medicine (500 from each organization). RESULTS: The overall response rate was 54%. The majority (78%) refer more than 50% of their GERD patients for EGD; however, 34% also refer more than 10% of their patients for barium studies. Primary care physicians cited alarm symptoms, refractory symptoms, and chronicity and severity of symptoms as the major indications for referral for EGD. Gender, age, obesity, and tobacco use were cited less frequently. Cost of endoscopy, poor patient acceptance, and lack of evidence were the most common reasons cited for not referring for EGD. A majority of respondents (62%) indicated that the availability of UE would increase referral for the procedure, and 52% would be willing to perform UE in their office. CONCLUSIONS: Severe, refractory, and chronic symptoms are the primary reasons for endoscopic referral from primary care physicians who manage patients with GERD. Other risk factors for BE, such as gender and age, do not appear to be important determinants for endoscopic referral. Further evaluation of UE as a mechanism to increase screening for BE in primary care patients is merited.

Attitude of Health Personnel↗
PubMed2006

Temporal trend in relative risk of second primary colorectal cancer.

BACKGROUND: Patients with colorectal cancer (CRC) are at a higher risk for developing a second primary. Factors (such as survival rate, rate of receipt of surveillance procedures, and the overall incidence of CRC) with potential impact on the risk for second primary CRC have changed over the last three decades. Thus, it is likely that the risk for second primary CRC also has changed over the years. OBJECTIVES: We used the Surveillance, Epidemiology, and End Results public-use database to assess whether the relative risk of second primary CRC has changed in patients with initial primary CRC. METHODS: The temporal trend in the standardized incidence ratio (SIR) for a second primary CRC was estimated. Also, the clinical features of the second primary CRC were compared in two subgroups based on the year of diagnosis of the first primary CRC: Group A (1973-1977) and Group B (1988-1992). RESULTS: During the period of 1973 to 2002, 216,751 patients developed a primary CRC and over a follow-up period of 1,250,687 person-years, 5,595 of these patients developed a second primary CRC, with an SIR of 1.36 (95% CI 1.32-1.39). In a Cox regression model, the period of diagnosis of the first primary CRC was an independent risk factor for a subsequent primary CRC, with a relative hazard of second colon cancer in Group B compared with Group A being 1.18 (95% CI 1.06-1.31), after controlling for age at diagnosis, site, stage of first primary, gender, and race. CONCLUSION: The relative risk of the second primary CRC has increased since early 1990s. These subsequent cancers are being diagnosed at an earlier stage. Increased surveillance may be one of the factors contributing to this temporal difference.

Aged↗
PubMed2006

Familiality in Barrett's esophagus, adenocarcinoma of the esophagus, and adenocarcinoma of the gastroesophageal junction.

BACKGROUND AND AIM: The familial aggregation of Barrett's esophagus, adenocarcinoma of the esophagus, and adenocarcinoma of the gastroesophageal junction, jointly termed familial Barrett's esophagus, may represent a complex genetic trait. The aim of this study was to determine the proportion of patients with these diseases who have familial Barrett's esophagus. METHODS: Information on gastroesophageal reflux symptoms, known risk factors for Barrett's esophagus, and family history of Barrett's esophagus and cancers, was collected at six hospitals using a structured questionnaire from probands with either long-segment Barrett's esophagus, adenocarcinoma of the esophagus, or adenocarcinoma of the gastroesophageal junction. Family history of Barrett's esophagus or esophageal cancer in a first- or second-degree relative was determined by reviewing medical records of all relatives reported to be affected. RESULTS: Seventy one of 411 (17.3%) probands reported an affected first- and/or second-degree relative. Upon review of medical records of the reportedly affected relatives, familial Barrett's esophagus was definitively determined in the case of 30 (7.3%) probands comprising 17 of 276 (6.2%) with Barrett's esophagus, 11 of 116 (9.5%) with adenocarcinoma of the esophagus, and 2 of 21 (9.5%) with adenocarcinoma of the gastroesophageal junction. The diagnosis in the relative reported by the proband to be affected was found not to be Barrett's esophagus or adenocarcinoma in 15 (3.6%) cases. The diagnosis could not be determined in 26 (6.3%) cases in which the proband reported an affected relative. There were no significant differences in age of disease onset, gender, race, or gastroesophageal reflux symptoms between definitive familial Barrett's esophagus probands and nonfamilial probands. CONCLUSION: Familial Barrett's esophagus can be confirmed in 7.3% of persons presenting with Barrett's esophagus, adenocarcinoma of the esophagus, or adenocarcinoma of the gastroesophageal junction.

Adenocarcinoma↗